MCQ 11 Mark
In a study of transistor as an amplifier, the ratio of collector current to emitter current is 0.98. The collector current is 3mA, then base current will be approximately ______.
MCQ 21 Mark
In a common emitter amplifier circuit using an n-p-n transistor, the phase difference between the input and the output voltages will be: ____________.
MCQ 31 Mark
Least doped region in a transistor ____________.
- A
- B
Either emitter or collector
- C
- ✓
View full question & answer→MCQ 41 Mark
The radius of orbit of an electron in hydrogen atom in its ground state is $5.3 \times 10^{-11} m$ After collision with an electron, it is found to have a radius of $13.25 \times 10^{-10} m$. The principal quantum number n of the final state of the atom is ______.
View full question & answer→MCQ 51 Mark
The ratio of the velocity of the electron in the first orbit to that in the second orbit is ____________.
MCQ 61 Mark
Which of the following transition will have highest emission wavelength?
MCQ 71 Mark
Graph shows the variation of de-Broglie wavelength `(lambda)` versus `1/sqrt"V"`, where 'V' is the accelerating potential for four particles carrying same charge but of masses $s m_1, m_2, m_3, m_4$ Which particle has a smaller mass?
- A
$m _1$
- B
$m_2$
- C
$m_3$
- ✓
$m_4$
View full question & answer→MCQ 81 Mark
The ratio of slopes m1: ro2 of the lines given in the following graphs is, ____
- ✓
- B
specific charge of electron (e/m)
- C
- D
View full question & answer→MCQ 91 Mark
The threshold frequency for a certain photosensitive metal is $v_0`$. When it is illuminated by light of frequency $v = 2v_0`,$ the maximum velocity of photoelectrons is $"v"_0`$. What will be the maximum velocity of the photoelectrons when the same metal is illuminated by light of frequencyv = 5v"v"_0`?
- A
$`sqrt2 "v"_0`$
- ✓
$2 v_0`$
- C
$`2 sqrt2 "v"_0`$
- D
$4 v_0`$
AnswerCorrect option: B. $2 v_0`$
View full question & answer→MCQ 101 Mark
In series resonant circuit, at resonance, ____________.
AnswerCorrect option: D. $Z = R$
View full question & answer→MCQ 111 Mark
The reactance of the coil is 20 `Omega` and its resistance is 20 `Omega`. It is connected to an A.C. source of e.m.f. 220 V. The peak value of the current in the circuit is ____________.
MCQ 121 Mark
Alternating current cannot be measured by D.C. ammeter because ____________.
- A
- ✓
average value of complete cycle is zero
- C
A.C. changes its direction
- D
A.C. cannot pass through D.C. ammeter
AnswerCorrect option: B. average value of complete cycle is zero
View full question & answer→MCQ 131 Mark
A straight conductor of length 2 m moves in a uniform magnetic field of induction 2.5 x `10^-3` T with a velocity. of 4 m/s in a direction perpendicular to its length and also perpendicular to the field. The e.m.f. induced between the ends of the conductor is ______.
MCQ 141 Mark
The rate of change of magnetic flux density through a circular coil of area $10^{-2} m^2$ and number of turns 200 is $10^3 Wb / m ^2 s$. The value of induced e.m.f. will be ...........
- A
$2 \times 10^{-2} V$
- B
$10^3 V$
- ✓
$2 \times 10^3 V$
- D
AnswerCorrect option: C. $2 \times 10^3 V$
View full question & answer→MCQ 151 Mark
In a coil of resistance 150 `Omega`, a current is induced by changing the magnetic flux through it as shown in the figure. The magnitude of change in flux through the coil is ____________.
MCQ 161 Mark
A bar magnet having length 5 cm and area of cross-section $4 cm^2$ has magnetic moment $2 Am ^2$. If magnetic susceptibility is $5 \times 10^{-6}$, the magnetic intensity will be .............
- A
$`5 xx 10^10 "A"/"m"`$
- B
$`0.5 xx 10^10 "A"/"m"`$
- ✓
$`2 xx 10^10 "A"/"m"`$
- D
$`0.2 xx 10^10 "A"/"m"`$
AnswerCorrect option: C. $`2 xx 10^10 "A"/"m"`$
View full question & answer→MCQ 171 Mark
A solenoid has core of a material with relative permeability 500 and its windings carry a current of 2 A. The number of turns of the solenoid is 500 per metre. The magnetization of the material is ______.
- ✓
$499 \times 10^3 Am ^{-1}$
- B
$500 \times 10^{-3} Am ^{-1}$
- C
$500 \times 10^5 Am ^{-1}$
- D
$499 \times 10^{-3} Am ^{-1}$
AnswerCorrect option: A. $499 \times 10^3 Am ^{-1}$
View full question & answer→MCQ 181 Mark
An electron of charge 'e' is revolving in a fixed orbit of radius 'r' with frequency 'f'. Its magnetic dipole moment is ____________.
MCQ 191 Mark
The magnetic induction at the centre of a coil made from a wire of length 44 m carrying a current of 0.5 A is nearly ____________.
- ✓
$4.5 \times 10^{-6} Wb / m ^2$
- B
$9 \times 10^{-6} Wb / m ^2$
- C
$0.8 \times 10^{-6} Wb / m ^2$
- D
$0.9 \times 10^{-6} Wb / m ^2$
AnswerCorrect option: A. $4.5 \times 10^{-6} Wb / m ^2$
View full question & answer→MCQ 201 Mark
Three long, straight and parallel wires carrying currents are arranged as shown in figure. The force experienced by 10 cm length of wire Q is ____________.
- A
$2.6 \times 10^{-4} N$ to the left
- B
$2.6 \times 10^{-4} N$ to the right
- ✓
$4 \times 10^{-5} N$ towards the right
- D
$4 \times 10^{-5} N$ towards the left
AnswerCorrect option: C. $4 \times 10^{-5} N$ towards the right
View full question & answer→MCQ 211 Mark
A proton describes a circular path of radius 5 cm in a transverse magnetic field. If the speed of proton is doubled, then the radius of the circular path will be ____________.
MCQ 221 Mark
A potentiometer wire has a length of 4m and resistance of 5Ω. It is connected in series with 495 Ω resistance and a cell of e.m.f. 4V. The potential gradient along the wire is ______
MCQ 231 Mark
In the potentiometer experiment, the balancing length with cell $E_1$ of unknown e.m.f. is $\ell_1 cm$. By shunting the cell $E_1$ with resistance ' $R$ ' which is equal to internal resistance $(r)$ of the cell $E_1$, the balancing length $\ell_2$ is ..........
- A
$`ℓ_1`$
- B
$`2ℓ_1`$
- C
$`ℓ_1/4`$
- ✓
$`ℓ_1/2`$
AnswerCorrect option: D. $`ℓ_1/2`$
View full question & answer→MCQ 241 Mark
In Wheatstone's network p = 2 `Omega` , Q = 2 `Omega`, R = 2 `Omega` and S = 3 `Omega`. The resistance with which S is to be shunted in order that the bridge may be balanced is ______.
MCQ 251 Mark
With resistances P and Q placed in the left and right gaps of a metre bridge, the balance point divides the wire in the ratio of 1/3. When P and Q are increased by 40 n each. the balance point divides the wire in the ratio of 3/5. The values of P and Q will be respectively, ______
MCQ 261 Mark
The capacity of the conductor does not depend upon ______
MCQ 271 Mark
Gauss' law helps in ____________.
- A
situations where Coulomb's law fails
- ✓
determination of electric field due to symmetric charge distribution
- C
determination of electric force between point charges
- D
determining electric potential due to symmetric charge distributions
AnswerCorrect option: B. determination of electric field due to symmetric charge distribution
View full question & answer→MCQ 281 Mark
In Young's double-slit experiment, an interference pattern is obtained on a screen by a light of wavelength $4000 \mathring A$, coming from the coherent sources $S_1$ and $S_2$ At certain point $P$ on the screen, third dark fringe is formed. Then the path difference $S_1 P-S_2 P$ in microns is ...........
View full question & answer→MCQ 291 Mark
In Young's double-slit experiment, if the width of the $2^{\text {nd }}$ bright fringe is $4 \times 10^{-2} cm$, then the width of the $4^{\text {th }}$ bright fringe will be....... cm .
- A
$1.5 \times 10^{-2}$
- B
$10^{-2}$
- C
$3 \times 10^{-2}$
- ✓
$4 \times 10^{-2}$
AnswerCorrect option: D. $4 \times 10^{-2}$
View full question & answer→MCQ 301 Mark
A thin wire of 99 cm is fixed at both ends as shown in figure. The wire is kept under a tension and is divided into three segments of lengths $l_1, l_2$, and $l_3$ as shown in figure. When the wire is made to vibrate respectively with their fundamental frequencies in the ratio $1: 2: 3$. Then the lengths $I _1, I _2$, and $I _3$ of the segments respectively are (in cm ).
View full question & answer→MCQ 311 Mark
The equation of a wave of amplitude 0.02 m and period 0.04 s travelling along a stretched string with a velocity of 25 m/s will be ____________.
- A
y = 0.02 sin 2`pi` (25t - 2x)
- B
y = 0.02 sin 2`pi` (0.04t - x)
- ✓
y = 0.02 sin 2`pi` (25t - x)
- D
y = 0.02 sin 2`pi` (0.04t - 0.5x)
AnswerCorrect option: C. y = 0.02 sin 2`pi` (25t - x)
View full question & answer→MCQ 321 Mark
Three masses 700 g, 500 g, and 400 g are suspended at the end of a spring and are in equilibrium as shown in figure. When the 700 g mass is removed, the system oscillates with a period of 3 seconds; when the 500 g mass is also removed, it will oscillate with a period of ____________.
MCQ 331 Mark
A particle starting from mean position oscillates simple harmonically with period 4 s. After what time will its kinetic energy be 75% of the total energy?
`( cos 30° = sqrt(3/2))`
MCQ 341 Mark
When heat energy of 2000 joules is supplied to a gas at constant pressure $2.1 \times 10^5 N / m ^2$, there is an increase in its volume equal to $2.5 \times 10^{-3} m^3$. The increase in internal energy of the gas in joules is ...............
View full question & answer→MCQ 351 Mark
A black rectangular surface of area A emits energy E per second at 27°C. If length and breadth is reduced to `(1/3)^("rd")` of initial value and temperature is raised to 327°C then energy emitted per second becomes ______.
MCQ 361 Mark
If 'f' is the number of degrees of freedom of a molecule of a gas and ratio of molar specific heats of a gas, ϒ = 1 + `2/"f"` where ϒ = Cp/Cv. The ratio of 'ϒ' for monoatomic gas to 'ϒ' for (rigid) f diatomic gas is ______.
MCQ 371 Mark
A small sphere of mass m is dropped from a great height. After it has fallen 100 m, it has attained its terminal velocity and continues to fall at that speed. The work done by air friction against the sphere during the first 100 m of fall is ______.
- A
- ✓
less than the work done by air friction in the second 100 m.
- C
- D
greater than the work done by air friction in the second 100 m.
AnswerCorrect option: B. less than the work done by air friction in the second 100 m.
View full question & answer→MCQ 381 Mark
The radius of curvature of a plane wavefront ______
- A
is less than that of a spherical wavefront.
- ✓
- C
is equal to the radius of curvature of a reversing wavefront.
- D
is slightly more than that of a cylindrical wavefront.
View full question & answer→MCQ 391 Mark
A body of mass 0.5 kg is rotating in a vertical circle of radius 2 m. What will be the difference in its kinetic energy at the top and bottom of the circle? (Take $g =9.8 m / s ^2$ )
View full question & answer→MCQ 401 Mark
Angular displacement (θ) of a flywheel varies with time as $\theta=a t+b t^2+c t^3$ then angular acceleration is given by ____________.
- A
$a+2 b-6 t$
- B
$a+2 b t-3 c t^2$
- C
$2 b-6 t$
- ✓
$2 b+6 c t$
AnswerCorrect option: D. $2 b+6 c t$
View full question & answer→MCQ 411 Mark
The width of depletion layer of a p-n junction diode, when it is (i) forward biased and (ii) reverse biased respectively ______.
MCQ 421 Mark
Polarised dielectric is equivalent to ______.
- A
- ✓
two charged surfaces with induced charges
- C
- D
AnswerCorrect option: B. two charged surfaces with induced charges
View full question & answer→MCQ 431 Mark
Time taken by sunlight to penetrate 2 mm through a glass slab is of the order ______.Refractive index of glass = 1.5, velocity of light in air $=3 \times 10^8 m / s$
- A
$10^{-19} s$
- B
$10^{-10} s$
- C
$10^5 s$
- ✓
$10^{-11} s$
AnswerCorrect option: D. $10^{-11} s$
View full question & answer→MCQ 441 Mark
Two monoatomic ideal gases A and B of molecular masses $' m_1$ ' and ' $m_2$ ' respectively, are enclosed in separate containers kept at the same temperature. The ratio of the speed of sound in gas A to that in gas B is given by ______.
- A
$`sqrt(m_1/m_2)`$
- ✓
$`sqrt(m_2/m_1)`$
- C
$`m_2/m_1`$
- D
$`m_1/m_2`$
AnswerCorrect option: B. $`sqrt(m_2/m_1)`$
View full question & answer→MCQ 451 Mark
At a certain instant, a stationary transverse wave is found to have maximum kinetic energy. The appearance of string at that instant is ____________.
- A
sinusoidal shape with amplitude `A/3`
- B
sinusoidal shape with amplitude A
- ✓
- D
sinusoidal shape with amplitude `A/2`
View full question & answer→MCQ 461 Mark
An iron plate has a circular hole of a diameter 11 cm. Find the diameter of the hole when the plate is uniformly heated from 10° C to 90° C.`[alpha = 12 xx 10^-6//°"C"]`
MCQ 471 Mark
A wire AB is carrying steady current '$I_1$' and is kept on the table. Another wire CD carrying current '$I_2$' is held parallel and directly above AB at a distance 'r'. When wire CD is left free and it remains suspended at its position, its mass per unit length is (g =acceleration due to gravity) ____________.
- A
$`(mu_0 "I"_1)/(2 pi"rg")`$
- B
$`(mu_0 "I"_1"I"_2)/(4 pi"rg")`$
- C
$`(mu_0 "I"_2)/(2 pi"rg")`$
- ✓
$`(mu_0 "I"_1"I"_2)/(2 pi"rg")`$
AnswerCorrect option: D. $`(mu_0 "I"_1"I"_2)/(2 pi"rg")`$
View full question & answer→MCQ 481 Mark
A planet is revolving around the sun in an elliptical orbit as shown in figure. At which point will its K.E. be maximum?
- A
$P _2$
- B
$P _3$
- ✓
$P _4$
- D
$P _1$
AnswerCorrect option: C. $P _4$
View full question & answer→MCQ 491 Mark
A see-saw of length 6 m is pivoted at its centre. A child of mass 20 kg is sitting at one of its ends. Where should another child, of mass 30 kg, sit on the other end from the centre of see-saw, so that it is balanced?
MCQ 501 Mark
A body of mass ·m' is moving along a circle of radius 'r' with linear speed 'v'. Now, to change the linear speed to `V/2` and to move it along the circle of radius '4r', required change in the centripetal force of the body is ______.
MCQ 511 Mark
Identify the CORRECT statement.
- ✓
A zero dimensional structure is one in which all three dimensions are in the nanoscale.
- B
Nanomaterials possess exactly the same properties as that of their bulk materials.
- C
Low surface-to-volume ratio is a very important characteristic of nanoparticles.
- D
Green chemistry is the combination of chemistry and nanoscience.
AnswerCorrect option: A. A zero dimensional structure is one in which all three dimensions are in the nanoscale.
View full question & answer→MCQ 521 Mark
Which among the following formula represents the ε-amino caproic acid?
- ✓
$H _2 N-\left( CH _2\right)_5- COOH$
- B
$\begin{array}{cc}
\phantom{......................}\ce{NH2}\\
\phantom{...................}|\\
\ce{H2N - CO - CH2 - CH}\\
\phantom{...................}|\\
\phantom{........................}\ce{COOH}
\end{array}$
- C
$\begin{array}{cc}
\ce{HO - CH2 - CH - COOH}\\
\phantom{..}|\\
\phantom{....}\ce{NH2}
\end{array}$
- D
$H _2 N- CH _2- COOH$
AnswerCorrect option: A. $H _2 N-\left( CH _2\right)_5- COOH$
View full question & answer→MCQ 531 Mark
Which of the following pair of compounds is used as monomers for bakelite?
AnswerCorrect option: C. HCHO and $C _6 H _5 OH$
View full question & answer→MCQ 541 Mark
Which of the following compounds is used to prepare orlon?
- A
$HOOC -\left( CH _2\right)_4- COOH$
- B
$CH _2= C \left( CH _3\right)_2$
- C
$H _2 C = CH - CH = CH _2$
- ✓
$CH _2= CH - CN$
AnswerCorrect option: D. $CH _2= CH - CN$
View full question & answer→MCQ 551 Mark
Which pair of bases is present both in DNA and RNA?
- A
- ✓
Adenine, guanine, cytosine
- C
Adenine, guanine, thymine
- D
AnswerCorrect option: B. Adenine, guanine, cytosine
View full question & answer→MCQ 561 Mark
Which of the following amino acids has $- CH _2 OH$ group in its side chain?
View full question & answer→MCQ 571 Mark
Choose the WRONG statement from the following.
- A
Denaturation of proteins is brought about by heating the proteins with alcohol or concentrated inorganic acids.
- ✓
Denaturation is a reversible process.
- C
Denaturation uncoils the protein.
- D
Denaturation results in the loss of biological activity.
AnswerCorrect option: B. Denaturation is a reversible process.
View full question & answer→MCQ 581 Mark
Which of the following amines liberates nitrogen gas when treated with nitrous acid?
AnswerCorrect option: A. $\left( CH _3\right)_2 CHNH _2$
View full question & answer→MCQ 591 Mark
Acylation of ethanamine to form N-ethylethanamide is an example of ____________ reaction.
- ✓
nucleophilic substitution
- B
- C
electrophilic substitution
- D
AnswerCorrect option: A. nucleophilic substitution
View full question & answer→MCQ 601 Mark
IUPAC name of $CH _3 N\left( C _2 H _5\right)_2$ is ________.
- A
- ✓
N-ethyl-N-methylethanamine
- C
- D
AnswerCorrect option: B. N-ethyl-N-methylethanamine
View full question & answer→MCQ 611 Mark
Identify X in the following reaction:
MCQ 621 Mark
The product of the reaction between dimethylcadmium and acetyl chloride is ____________.
- A
$CH _3 CHO$
- ✓
$CH _3 COCH _3$
- C
$C _2 H _5 COC _2 H _5$
- D
$CH _3 COC _2 H _5$
AnswerCorrect option: B. $CH _3 COCH _3$
View full question & answer→MCQ 631 Mark
In the formation of an aldol, α-carbon atom of one aldehyde molecule attaches to ____________ of another aldehyde molecule.
MCQ 641 Mark
What is IUPAC name of mesityl oxide?
MCQ 651 Mark
A mixed ether on hydrolysis gives ____________.
- A
- B
- C
one alcohol and one alkyl halide
- ✓
View full question & answer→MCQ 661 Mark
Identify the reagent A used in the following conversion.$\ce{Phenol ->[A] Benzoquinone}$
- ✓
$Na _2 Cr _2 O _7+ H _2 SO _4$
- B
$\text { conc. } H _2 SO _4$
- C
$NaOH , CO _2$
- D
$CHCl _3+\text { aq. } NaOH$
AnswerCorrect option: A. $Na _2 Cr _2 O _7+ H _2 SO _4$
View full question & answer→MCQ 671 Mark
Identify the product B in following conversion. $\ce{Chlorobenzene + H2O ->[Cu, 673 K][Pressure] A ->[conc. H2SO4][373 K] B}$
- ✓
4-Hydroxybenzene sulphonic acid
- B
2-Hydroxybenzene sulphonic acid
- C
3-Hydroxybenzene sulphonic acid
- D
AnswerCorrect option: A. 4-Hydroxybenzene sulphonic acid
View full question & answer→MCQ 681 Mark
Identify the product and it's quantity obtained when 9.2 g ethanol is treated with acidified potassium dichromate under ideal conditions?
MCQ 691 Mark
The $S _{ N } 2$ reaction of a compound containing an asymmetric carbon atom always gives ____________.
- ✓
a product with opposite optical rotation
- B
a metamer of the substrate
- C
- D
a mixture of cis-trans isomers
AnswerCorrect option: A. a product with opposite optical rotation
View full question & answer→MCQ 701 Mark
Which among the following has highest boiling point?
MCQ 711 Mark
What is the IUPAC name of neopentyl chloride?
- A
- B
3-Chloro-2, 2-dimethylpropane
- C
- ✓
1-Chloro-2, 2-dimethylpropane
AnswerCorrect option: D. 1-Chloro-2, 2-dimethylpropane
View full question & answer→MCQ 721 Mark
The number of unpaired electrons in the complex ion $\left[ CoF _6\right]^{3-}$ is ____________.
View full question & answer→MCQ 731 Mark
____________ isomers are formed when the ligand has two different donor atoms.
MCQ 741 Mark
Which coordinate complex from the following has a complex ion with positive charge?
- A
$K _2\left[ Hgl _4\right]$
- B
$\left[ Pt \left( NH _3\right)_2 Cl _2\right]$
- C
$K _4\left[ Fe ( CN )_6\right]$
- ✓
$\left[ Ni \left( NH _3\right)_6\right] Cl _2$
AnswerCorrect option: D. $\left[ Ni \left( NH _3\right)_6\right] Cl _2$
View full question & answer→MCQ 751 Mark
What is the formula of pyrolusite ore?
- A
$Cr _2 O _3$
- B
$Cu _2 O$
- C
$PbCrO _4$
- ✓
$MnO _2$
AnswerCorrect option: D. $MnO _2$
View full question & answer→MCQ 761 Mark
Nichrome is used specifically for making ____________.
MCQ 771 Mark
Which of the following statements is INCORRECT?
- A
Li and Mg form corresponding nitrides on reaction with $N _2$.
- B
LiCl and $MgCl _2$ are soluble in ethanol.
- ✓
$Li _2 O$ and MgO form super oxides on reaction with excess of $O _2$.
- D
LiCl and $MgCl _2$ form corresponding hydrates on crystallization from their aqueous solutions.
AnswerCorrect option: C. $Li _2 O$ and MgO form super oxides on reaction with excess of $O _2$.
View full question & answer→MCQ 781 Mark
Which of the following structure represents thiosulfuric acid?
MCQ 791 Mark
The time taken for 80% of a first order reaction to be complete is approximately ____________.
- A
$3.3 \times t _{1 / 2} \times \log _{10} 20$
- B
$3.3 \times t _{1 / 2} \times \log _{10} 10$
- ✓
$3.3 \times t _{1 / 2} \times \log _{10} 5$
- D
$3.3 \times t _{1 / 2} \times \log _{10} 80$
AnswerCorrect option: C. $3.3 \times t _{1 / 2} \times \log _{10} 5$
View full question & answer→MCQ 801 Mark
A chemical species that is formed in one elementary step in the mechanism of complex reaction and consumed in the subsequent step is called ____________.
MCQ 811 Mark
Which of the following reactions represents enthalpy of formation of NaCl?
- A
$\ce{Na^+_{( aq)} + Cl^-_{( aq)} -> NaCl_{(s)}}$
- ✓
$\ce{Na_{(s)} + 1/2Cl2_{(g)} -> NaCl_{(s)}}$
- C
$\ce{Na_{(s)} + AuCl_{(s)} -> NaCl_{(s)} + Au_{(s)}}$
- D
$\ce{NaCl_{(s)} -> Na_{(s)} + 1/2Cl2_{(g)}}$
AnswerCorrect option: B. $\ce{Na_{(s)} + 1/2Cl2_{(g)} -> NaCl_{(s)}}$
View full question & answer→MCQ 821 Mark
Which among the following solution has the highest conductivity (k) value?
MCQ 831 Mark
Which of following is residual entropy of a substance?
- ✓
entropy of solid greater than 0 at T = 0 K
- B
entropy of solid greater than 0 at T = 273 K
- C
entropy of solid equal to 0 at T = 0
- D
entropy of solid equal to 0 at T = 273 K
AnswerCorrect option: A. entropy of solid greater than 0 at T = 0 K
View full question & answer→MCQ 841 Mark
The enthalpy change accompanying a reaction in which 1 mole of the substance in the standard state reacts completely with oxygen or is completely burnt is called as ____________.
- A
standard heat of formation
- B
standard enthalpy of neutralization
- C
- ✓
standard enthalpy of combustion
AnswerCorrect option: D. standard enthalpy of combustion
View full question & answer→MCQ 851 Mark
$NH_4CN$ is a salt of ____________.
- A
strong acid and weak base
- B
weak acid and strong base
- ✓
- D
strong acid and strong base
View full question & answer→MCQ 861 Mark
According to the Bronsted-Lowry theory, an acid is a substance that ____________.
- A
- B
accepts a proton from another substance
- C
- ✓
donates a proton to another substance
AnswerCorrect option: D. donates a proton to another substance
View full question & answer→MCQ 871 Mark
A solution containing 1 mole of solute has an osmotic pressure of $4 \times 10^5 N m ^2$ at 300 K . Calculate its volume if 1 mole of same solute in $12 m^3$ has an osmotic pressure of $3 \times 10^5 N m ^2$ at the same temperature.
- A
$3 m^3$
- B
$12 m^3$
- ✓
$9 m^3$
- D
$6 m^3$
AnswerCorrect option: C. $9 m^3$
View full question & answer→MCQ 881 Mark
For which solution, the depression in freezing point equals the cryoscopic constant for the solvent?
MCQ 891 Mark
In ABCABC type arrangement of spheres, the coordination number of any sphere is __________.
MCQ 901 Mark
An element (atomic mass $M g / mol$ ) having bcc structure has unit cell edge 400 pm . The density of the element is ........... $g / cm ^3$.
$\left[N_A=6.0 \times 10^{23} \text { atom } mol ^{-1}\right)$
View full question & answer→MCQ 911 Mark
Addition of hydrogen bromide to but-2-ene and but-1-ene forms ______.
- A
2 - bromobutane and 1 -bromobutane respectively
- B
- ✓
- D
1 - bromobutane and 2- bromobutane respectively
View full question & answer→MCQ 921 Mark
Which of the following statements is INCORRECT for the organic compounds which belong to homologous series?
AnswerCorrect option: D. They have different chemical and physical properties.
View full question & answer→MCQ 931 Mark
Which of the following is a heterogeneous mixture?
- A
Mixture of salt and water
- B
- ✓
- D
Aqueous solution of sugar
View full question & answer→MCQ 941 Mark
At constant temperature, a quantity of an ideal gas occupies 50 mL at 500 mmHg pressure. At what pressure, the volume will be 100 mL?
MCQ 951 Mark
According to Andrews isothermals at what temperature the carbon dioxide gas starts to condense at 73 atmosphere?
MCQ 961 Mark
Which of the following is the CORRECT order for alkaline earth metals?
- ✓
Ca < Mg < Be < Sr < Ba (Density)
- B
Be < Mg < Ca < Ba < Sr (Atomic radii)
- C
Be < Mg < Ca < Sr < Ba (Second ionization enthalpy)
- D
Be < Mg < Ca < Sr < Ba (First ionization enthalpy)
AnswerCorrect option: A. Ca < Mg < Be < Sr < Ba (Density)
View full question & answer→MCQ 971 Mark
If the standard electrode potential of $Cu ^{2+} / Cu$ electrode is 0.34 V , what is the electrode potential if concentration of $Cu ^{2+}$ ions is $0.01 M ( T =298 K)$ ?
View full question & answer→MCQ 981 Mark
What is the formal charge on hydrogen atom in water molecule?
MCQ 991 Mark
The radius of the third Bohr orbit for hydrogen atom is ____________.
MCQ 1001 Mark
The unit of atomic mass, amu is replaced by u, here u stands for ______.
MCQ 1011 Mark
Species that possess a very high risk of extinction due to population decline of about 30 - 50 % over past 10 years are categorized as _______.
MCQ 1021 Mark
How many million species are been documented as per IUCN data (2004)?
MCQ 1031 Mark
Which of the following is an observation of Alexander von Humboldt's documented pattern in ecology?
- A
Species richness decreases with increasing explored area upto the given limit.
- B
Species richness is not related to the area explored.
- C
Species richness is almost constant with increasing explored area upto the given limit.
- ✓
Species richness increases with increasing explored area upto the given limit.
AnswerCorrect option: D. Species richness increases with increasing explored area upto the given limit.
View full question & answer→MCQ 1041 Mark
The 'rivet' in the rivet popper hypothesis is considered to represent the ______.
MCQ 1051 Mark
Number of national parks and sanctuaries in Maharashtra are around ____________ and ____________ respectively.
MCQ 1061 Mark
Identify the stage that is common to both hydrarch and xerarch succession.
MCQ 1071 Mark
In what state is the climax community?
MCQ 1081 Mark
What is the term used to denote the gradual and predictable change in the species composition of a given area?
MCQ 1091 Mark
What is the dissolved salt concentration (in ppm) of the sea?
MCQ 1101 Mark
The interspecific interaction between Cuckoo and Crow is ______
MCQ 1111 Mark
What will be the birth rate per individual per hour of a population of 50 Paramoecium present in a pool. The population of Paramoecium increases to 150 within an hour.
MCQ 1121 Mark
Read the given statement and choose the correct option. Statement I: Polar animals have a thick layer of fat below skin.
Statement II: The blubber below polar animals' skin allows heat from outside to enter into the body.
- A
Neither statement I nor II are correct
- ✓
- C
Both statements I and II are correct
- D
View full question & answer→MCQ 1131 Mark
Identify the term used to denote the functional role played by an organism in its environment.
MCQ 1141 Mark
Which organisms are restricted to a narrow range of salinities?
MCQ 1151 Mark
Which of the following method is applied to obtain a desirable change in genotype of an organism?
MCQ 1161 Mark
Which of the following diseases is Treated using Protein α-1- antitrypsin?
MCQ 1171 Mark
______ are NOT polymeric in nature.
MCQ 1181 Mark
Which of the following method was used to develop insect pest resistant Bt-cotton plant?
MCQ 1191 Mark
During gene cloning, the enzyme ______ is used to join the gene of interest with the plasmid vector.
MCQ 1201 Mark
Which of the following is/are symbiotic nitrogen fixing microbe?
MCQ 1211 Mark
Identify the INCORRECT statement regarding Bacillus thuringiensis.
- A
It is used to get rid of butterfly, caterpillars.
- ✓
It is a free-living fungi found in the root ecosystem.
- C
Dried spores of Bacillus thuringiensis are mixed with water and sprayed onto vulnerable plants.
- D
It is an example of microbial biocontrol agent.
AnswerCorrect option: B. It is a free-living fungi found in the root ecosystem.
View full question & answer→MCQ 1221 Mark
Identify the TRUE statement/s regarding biogas.
- A
It is a conventional source of energy.
- B
lt is obtained by microbial fermentation.
- ✓
Both It is obtained by microbial fermentation and It is a mixture of $CH _4, CO _2, H _2 S$, and other gases.
- D
It is a mixture of $CH _4, CO _2, H _2 S$, and other gases.
AnswerCorrect option: C. Both It is obtained by microbial fermentation and It is a mixture of $CH _4, CO _2, H _2 S$, and other gases.
View full question & answer→MCQ 1231 Mark
Small part of activated sludge is passed back into ______ and major part is pumped into large tanks called ______.
- A
sedimentation tank; grit chambers
- B
primary sedimentation tank; aeration tank
- C
anaerobic bioreactor; grit chambers
- ✓
aeration tank; anaerobic sludge digesters
AnswerCorrect option: D. aeration tank; anaerobic sludge digesters
View full question & answer→MCQ 1241 Mark
Identify the organism used in production of alcohol.
- A
Streptococcus thermophilus
- B
Propionibacterium shermanii
- ✓
- D
View full question & answer→MCQ 1251 Mark
____________ is released during rupture of oocyst of malarial parasite.
MCQ 1261 Mark
Ascariasis can be treated using ______.
- A
Chloromycetin, Diethylcarbamazine, Nystatin
- B
Fluconazole, Itraconazole, Nystatin
- C
Itraconazole, Diethylcarbamazine, Levamisole
- ✓
Mebendazole, Piperazine, Levamisole, Pyrantel
AnswerCorrect option: D. Mebendazole, Piperazine, Levamisole, Pyrantel
View full question & answer→MCQ 1271 Mark
In the given structure of an antibody molecule, identify the label 'X'.
- A
Constant region of heavy chain
- B
Constant region of light chain
- C
- ✓
View full question & answer→MCQ 1281 Mark
Sensitized helper T-cells produce ____________.
MCQ 1291 Mark
The type of immunity generated by the transfer of lgA from mother to child is ____________.
- A
artificial acquired active immunity
- B
natural acquired active immunity
- ✓
natural acquired passive immunity
- D
artificial acquired passive immunity
AnswerCorrect option: C. natural acquired passive immunity
View full question & answer→MCQ 1301 Mark
What are the properties of skin that make it a part of the innate immune system?
- ✓
- B
It possesses bactericidal activity
- C
It bas high concentrations of salt in drying sweat
- D
Sebaceous secretions have fungicidal properties
View full question & answer→MCQ 1311 Mark
Which of the following is the correct description of Gyri and sulci?
- A
They are grooves and convolutions respectively in cerebrum
- B
They are convolutions and grooves respectively in cerebrum
- C
They are grooves and convolutions respectively in cerebral hemispheres
- ✓
They are convolutions and grooves respectively in cerebral hemispheres
AnswerCorrect option: D. They are convolutions and grooves respectively in cerebral hemispheres
View full question & answer→MCQ 1321 Mark
Identify the lobe which has centre for visual functions.
MCQ 1331 Mark
Identify the value of action potential.
MCQ 1341 Mark
What are the number of $Na ^{+}$ions pumped out, and $K ^{+}$ions pumped into the cell, with respect to the $Na ^{+}- K ^{+}$ pump?
- A
$3 Na ^{+}, 3 K$
- ✓
$3 Na ^{+}, 2 K^{+}$
- C
$2 Na ^{+}, 3 K^{+}$
- D
$2 Na ^{+}, 2 K^{++}$
AnswerCorrect option: B. $3 Na ^{+}, 2 K^{+}$
View full question & answer→MCQ 1351 Mark
Which cells are responsible for formation of myelin sheath?
- A
Oligodendrocytes and Osteoclasts
- ✓
Schwann Cells and Oligodendrocytes
- C
Astrocytes and Schwann Cells
- D
Osteoclasts and Astrocytes
AnswerCorrect option: B. Schwann Cells and Oligodendrocytes
View full question & answer→MCQ 1361 Mark
What does the neural tissue consist of?
MCQ 1371 Mark
From the following identify the normal haemoglobin count in adult male.
- A
10 - 12 gm/1000 ml of blood
- B
11.5 - 16.5 mg/100ml of blood
- ✓
14 - 17 gm/100 ml of blood
- D
AnswerCorrect option: C. 14 - 17 gm/100 ml of blood
View full question & answer→MCQ 1381 Mark
What is the location of maturation of T-lymphocytes?
MCQ 1391 Mark
Normally, human adults breathe $\text{i} ...... \text{times}/\min$ while a new born breathe $\text{ii} ....... \text{times}/\min$.
- ✓
$12-14$ and $44$
- B
$30-40$ and $10-12$
- C
$50-60$ and $44$
- D
$44$ and $12-14$
AnswerCorrect option: A. $12-14$ and $44$
$12-14$ and $44$
View full question & answer→MCQ 1401 Mark
______ is formed when carbon monoxide combines with haemoglobin.
MCQ 1411 Mark
Due to which of the following reason lungs do not collapse between breaths and some air always remains in the lungs which can never be expelled?
- A
There is a positive intra-pleural pressure.
- B
There is a negative pressure in the lungs.
- ✓
There is a negative intra-pleural pressure pulling at the lung walls.
- D
Pressure in the lungs is higher than the atmospheric pressure.
AnswerCorrect option: C. There is a negative intra-pleural pressure pulling at the lung walls.
View full question & answer→MCQ 1421 Mark
Which of the following features the respiratory surface should have for efficient gaseous exchange?
- A
It should have a large surface area.
- B
It should be thin, highly vascular and permeable to allow exchange of gases.
- C
- ✓
View full question & answer→MCQ 1431 Mark
Which of the following indicates the shift of oxyhaemoglobin dissociation curve due to change in $ppCO _2$ in blood?
- A
- B
Carbon monoxide poisoning
- C
- ✓
View full question & answer→MCQ 1441 Mark
Which free living microorganism helps in nitrogen fixation?
MCQ 1451 Mark
______ is growth inhibitor.
MCQ 1461 Mark
Which among the following is NOT a physiological role of abscisic acid?
- ✓
It inhibits flowering in short day plants but stimulates flowering in long day plants.
- B
It acts as a stress hormone by inducing the plant to bear the adverse environmental conditions.
- C
It is synthesized in leaves, fruits, roots, seeds etc.
- D
It controls the dormancy in buds and seeds by inhibiting growth processes.
AnswerCorrect option: A. It inhibits flowering in short day plants but stimulates flowering in long day plants.
View full question & answer→MCQ 1471 Mark
______ enhances internodal elongation.
MCQ 1481 Mark
Identify the components by which cell wall of root hair is formed.
- A
- ✓
Pectic compounds and cellulose
- C
- D
AnswerCorrect option: B. Pectic compounds and cellulose
View full question & answer→MCQ 1491 Mark
Identify the part of the plants which is responsible for maximum absorption of water.
MCQ 1501 Mark
Which part of the root helps in maximum absorption of water and minerals?
MCQ 1511 Mark
All of the following are the properties of water, EXCEPT
- ✓
It provides energy necessary for most of the chemical reactions.
- B
It is a best transporting medium for dissolved minerals and food molecules.
- C
It is a best aqueous medium for all biochemical reactions occurring in the cells.
- D
It is a best solvent for most of the solutes.
AnswerCorrect option: A. It provides energy necessary for most of the chemical reactions.
View full question & answer→MCQ 1521 Mark
In plants, which zone/region/part is responsible for maximum absorption of water?
MCQ 1531 Mark
Identify the CORRECT match.
- A
Neanderthal man - Nicknamed handy man
- ✓
Australopithecus - Man with ape brain
- C
Dryopithecus - Erect posture
- D
Homo erectus - Brain size around 1400cc
AnswerCorrect option: B. Australopithecus - Man with ape brain
View full question & answer→MCQ 1541 Mark
Complete the following analogy. ______ : Man-like :: Dryopithecus : Ape-like hairy primate
MCQ 1551 Mark
Which statements are $\text{TRUE}$ regarding genetic recombination?
$\text{(i)}$ It occurs in asexually and sexually reproducing organisms.
$\text{(ii)}$ They occur due to random union of gametes, anaphasic separation of chromosomes, and crossing over.
$\text{(iii)}$ New genetic combinations result in variation.
- A
$\text{i, ii,}$ and $\text{iii}$
- B
$\text{i}$ and $\text{iii}$
- C
$\text{i}$ and $\text{ii}$
- ✓
$\text{ii}$ and $\text{iii}$
AnswerCorrect option: D. $\text{ii}$ and $\text{iii}$
$\text{ii}$ and $\text{iii}$
View full question & answer→MCQ 1561 Mark
Modem synthetic theory encompasses which of the following concepts?
MCQ 1571 Mark
All are post zygotic barriers, EXCEPT
- A
- B
Formation of intergeneric hybrid which is sterile
- ✓
Difference in structure of reproductive organs
- D
Union of gametes does not occur on time
AnswerCorrect option: C. Difference in structure of reproductive organs
View full question & answer→MCQ 1581 Mark
____________ paper is used for embedding DNA strands in Southern blotting technique.
MCQ 1591 Mark
In which of the following year the Human Genome Project (HGP) was initiated?
MCQ 1601 Mark
Which of the following term refers to the study of genomes through analysis, sequencing and mapping of genes along with the study of their functions?
MCQ 1611 Mark
Identify the event that would occur in 'lac operon' of E. coli when the growth medium has high concentration of lactose.
- A
The repressor protein attaches to the promoter sequence and derepresses the operator.
- B
The structural genes fail to produce polycistronic RNA.
- ✓
The inducer molecule binds to repressor protein and RNA polymerase binds to promoter sequence.
- D
The repressor protein binds to RNA polymerase and prevents translation.
AnswerCorrect option: C. The inducer molecule binds to repressor protein and RNA polymerase binds to promoter sequence.
View full question & answer→MCQ 1621 Mark
Identify the INCORRECT statement.
- ✓
In prokaryotes, the primary mRNA transcripts undergo splicing.
- B
Monocistronic mRNA is produced in eukaryotes.
- C
In Prokaryotes, sigma subunit of RNA polymerase recognizes the promoter.
- D
Transcription refers to the process of formation of mRNA from DNA.
AnswerCorrect option: A. In prokaryotes, the primary mRNA transcripts undergo splicing.
View full question & answer→MCQ 1631 Mark
Which of the following is TRUE with respect to the genes which inherit together during crossing over?
- A
- ✓
Both are tightly linked and They show low recombination.
- C
- D
They show low recombination.
AnswerCorrect option: B. Both are tightly linked and They show low recombination.
View full question & answer→MCQ 1641 Mark
Which of the following is a primary constriction?
MCQ 1651 Mark
Mendel may not be able to establish the law of independent assortment, if both characters were located on ____________.
- A
separate chromosome but at different loci.
- ✓
same homologous chromosomes.
- C
- D
separate homologous chromosomes.
AnswerCorrect option: B. same homologous chromosomes.
View full question & answer→MCQ 1661 Mark
Which of the following is CORRECT with respect to alleles or allelomorphs?
- A
Alleles are two or more alternative forms of genes that occupy different position on homologous chromosomes.
- B
Alleles are two or more alternative forms of genes that occupy different position on heterozygous chromosomes.
- C
Alleles are genes that occupy same position on heterozygous chromosomes.
- ✓
Alleles are two or more alternative forms of a gene which occupy same position on homologous chromosomes.
AnswerCorrect option: D. Alleles are two or more alternative forms of a gene which occupy same position on homologous chromosomes.
View full question & answer→MCQ 1671 Mark
Some individuals with blood group B may inherit the genes for black hair, while other individuals with blood group B may inherit the genes for brown hair. This can be explained by the principle of ____________.
MCQ 1681 Mark
In a dihybrid cross with contrasting characters, the number of different genotypes obtained in $F_2$ generation are ______.
View full question & answer→MCQ 1691 Mark
Identify the INCORRECT statement.
- A
Menstruation does not occurs after the ovum is fertilized.
- B
High level of progesteron stimulates the thickening of endometrium.
- ✓
Menstrual cycle continues throughout lifetime in human females.
- D
Reproductive phase extends between menarche and menopause.
AnswerCorrect option: C. Menstrual cycle continues throughout lifetime in human females.
View full question & answer→MCQ 1701 Mark
Match the Columns. | | Column I | | Column II |
| i. | Proliferative phase | a. | Breakdown of the endometrial lining |
| ii. | Secretory phase | b. | Follicular phase |
| iii. | Menstruation | c. | Luteal phase |
MCQ 1711 Mark
All are associated with ovulation in human female, EXCEPT
- A
Release of secondary oocyte
- B
- C
Full development of Graafian follicle
- ✓
View full question & answer→MCQ 1721 Mark
Semen is secreted by ______.
- A
- B
- ✓
epididymis and accessory glands
- D
AnswerCorrect option: C. epididymis and accessory glands
View full question & answer→MCQ 1731 Mark
Cowper's gland is homologous in function to ______
MCQ 1741 Mark
Identify the condition in wtrich the testis fails to descend from abdomen into scrotum, leading to sterility.
MCQ 1751 Mark
From the following which one is NOT a disadvantage of self-pollination?
- A
Less adaptability to climatic variations
- B
- ✓
Genetic stability can be maintained
- D
No scope for developing improved varieties
AnswerCorrect option: C. Genetic stability can be maintained
View full question & answer→MCQ 1761 Mark
Adventive embryony can be observed in ______.
MCQ 1771 Mark
Identify the function of micropyle in seed.
- A
Entry of water during germination
- ✓
Both Entry of water during germination and Entry of oxygen during germination
- C
Entry of oxygen during germination
- D
Acts as a first photosynthetic organ
AnswerCorrect option: B. Both Entry of water during germination and Entry of oxygen during germination
View full question & answer→MCQ 1781 Mark
In which of the following the primary endosperm nucleus undergoes free nuclear division or karyokinesis?
MCQ 1791 Mark
Due to which of the following reasons the pollen tube usually grows down towards the egg?
- ✓
The filiform apparatus of synergids is believed to attract the pollen tube.
- B
Pollen tube grows under control of nucleus.
- C
Pollen tube has no other passage to follow.
- D
The egg cell attracts the pollen tube as they have dissimilar electric charge.
AnswerCorrect option: A. The filiform apparatus of synergids is believed to attract the pollen tube.
View full question & answer→MCQ 1801 Mark
How many meiotic divisions are required to produce 576 haploid microspores if there are 24 microspore mother cells?
MCQ 1811 Mark
Stones formed when the urinary tract is infected by urea splitting bacteria are ______
MCQ 1821 Mark
Diabetes insipidus is caused due to ____________.
- A
- ✓
- C
- D
$Ca ^{2+}$ deficiency
View full question & answer→MCQ 1831 Mark
In persons with normal renal function, the glomerulus filters about ______.
MCQ 1841 Mark
The human kidney is histologically divided into ____________.
- A
outer pelvis and inner cortex
- ✓
outer cortex and inner medulla
- C
outer fascia and inner medulla
- D
outer renal cortex and inner pith
AnswerCorrect option: B. outer cortex and inner medulla
View full question & answer→MCQ 1851 Mark
The function of PCT of the kidney is ______.
- A
- ✓
Selective reabsorption of electrolytes
- C
- D
AnswerCorrect option: B. Selective reabsorption of electrolytes
View full question & answer→MCQ 1861 Mark
Loss of apetite, acidity, regurgitation, and dyspepsia after consuming spicy food are symptoms of ______.
MCQ 1871 Mark
- A
water, drugs, and vitamins
- B
- C
- ✓
lipids and fat-soluble vitamins
AnswerCorrect option: D. lipids and fat-soluble vitamins
View full question & answer→MCQ 1881 Mark
All enzymes are present in succus entericus, EXCEPT
MCQ 1891 Mark
____________ temporarily stores undigested waste material called faeces.
MCQ 1901 Mark
Match the Column I with Column II and select the correct option. | Column I | Column II |
| i. Heterodont | a. Teeth embedded in separate sockets in jaw bone |
| ii. Diphyodont | b. Four sets of teeth |
| iii. Thecodont | c. Two sets of teeth in lifetime |
MCQ 1911 Mark
Which of the following statement/s are CORRECT with respect to ETS?
i. In this process, energy is released in a controlled and stepwise manner to prevent any damage to the cell.
ii. ETS produces water molecules.
iii. Oxidized coenzymes such as NAD and FAD are regenerated from their reduced forms ( $NADH + H ^{+}$and FADH ${ }^2$ ) for recycling.
iv. Major amount of energy is generated through ETS or terminal oxidation in the form of ATP molecules.
v. Per glucose molecule 38 ATP molecules are formed, out of which 34 ATP molecules are produced through ETS.
View full question & answer→MCQ 1921 Mark
____________ catalyzes the conversion of glucose-6-phosphate to fructose-6-phosphate.
MCQ 1931 Mark
ATP is used in glycolysis to phosphorylate ______.
- A
triose to triose phosphate
- B
phosphoglycerate to phosphoenol pyruvate
- C
phosphoenolpyruvic acid to pyruvic acid
- ✓
hexose to hexose phosphate
AnswerCorrect option: D. hexose to hexose phosphate
View full question & answer→MCQ 1941 Mark
During which of the following process oxidative phosphorylation occurs in eukaryotes?
MCQ 1951 Mark
Identify the enzyme that converts pyruvate to acetyl CoA and $CO _2$.
View full question & answer→MCQ 1961 Mark
Maltose is composed of ______.
MCQ 1971 Mark
Study the following statements and select correct option.
Statement I: Removal of co-factors from the enzyme disrupts the catalytic activity of the enzyme.
Statement II: Prosthetic groups bound tightly to apoenzymes in order to make them catalytically active.
- A
Statement I is correct while Statement 11 is incorrect.
- ✓
Both the statements are correct.
- C
Statement I is incorrect while Statement II is correct.
- D
Both the statements are incorrect.
AnswerCorrect option: B. Both the statements are correct.
View full question & answer→MCQ 1981 Mark
Identify the INCORRECT match.
- ✓
Thymine, Guanine → Pyrimidine
- B
Cytosine, Uracil → Pyrimidine
- C
Adenine, Guanine → Purines
- D
Cytosine, Thymine → Pyrimidine
AnswerCorrect option: A. Thymine, Guanine → Pyrimidine
View full question & answer→MCQ 1991 Mark
Identify 'P' and 'Q' in the following table. | Proteins | Role |
| immunoglobulin | P |
| Q | Blood clotting |
- A
P: Structural stability of cell
Q: Fibrinogen
- ✓
P: Resistance against diseases
Q: Fibrinogen
- C
P: Transport of Oxygen
Q: Haemoglobin
- D
P: Muscle contraction
Q: Fibrinogen
AnswerCorrect option: B. P: Resistance against diseases
Q: Fibrinogen
View full question & answer→MCQ 2001 Mark
Formation of lactose by conden ation results in the release of how many molecules of water?
