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JEE physics MCQ

Universe · CBSE STD 12 Science (CBSE - English Medium). 67 questions.

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50 questions · auto-graded multiple-choice test.

MCQ 11 Mark
Meteors are
  • A
    Small stars
  • ✓
    Burnt pieces of comets that fall on earth
  • C
    Comets without tails
  • D
    None of these
Answer
Correct option: B.
Burnt pieces of comets that fall on earth
Meteors are burnt piece of comet. When they reach earth's atmosphere, they start burning due to friction.
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MCQ 21 Mark
According to the pulsating theory the expansion and contraction of the universe repeats after every
  • A
    $11$ years
  • B
    $8$ billion years
  • C
    $8$ million years
  • ✓
    $80$ billion years
Answer
Correct option: D.
$80$ billion years
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MCQ 31 Mark
Two stars $P$ and $Q$ are observed at night. Star $P$ appears reddish while, star $Q$ is white. From this we conclude
  • ✓
    Temperature of $Q$ is higher than that of $P$
  • B
    Temperature of $Q$ is lower than that of $P$
  • C
    Star $Q$ is at the same distance at that of $\operatorname{star} P$
  • D
    Star $P$ is farther than star $Q$
Answer
Correct option: A.
Temperature of $Q$ is higher than that of $P$
The star which appears red is at less temperature, than the star which appears white. Therefore, temperature of $Q$ is higher than that of $P$.
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MCQ 41 Mark
How does the red shift confirms that the universe is expanding
  • A
    Due to Wien's law
  • B
    Due to Stefan's law
  • C
    Due to Kirchhoff's law
  • ✓
    Due to Doppler's effect
Answer
Correct option: D.
Due to Doppler's effect
If the light received from galaxies indicates a shift towards the red end of spectrum of light, it means that the galaxies should be receding away (Doppler's effect). Therefore we conclude that the universe is expanding.
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MCQ 51 Mark
The tail of the comet is due to
  • ✓
    Vaporisation of water on the comet
  • B
    Sublimation of vapour in the comet
  • C
    Cooling of water in the comet
  • D
    Vaporisation of heat in the comet
Answer
Correct option: A.
Vaporisation of water on the comet
If a comet approaches the sun, the substances like water etc. on the comet, get vaporised due to the heat of Sun, and radiation pressure forces of these vapours move away from the Sun. Hence, it forms the tail of the comet.
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MCQ 61 Mark
'Albedo' is
  • ✓
    Reflecting power of a heavenly body
  • B
    Transmitive power of a heavenly body
  • C
    Absorptive power of a heavenly body
  • D
    Refracting power of a heavenly body
Answer
Correct option: A.
Reflecting power of a heavenly body
Reflecting power of a heavenly body is called albedo.
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MCQ 71 Mark
When original mass of star is greater than $5 M(M=$ mass of the sun). The death of this star will give rise to
  • A
    White dwarf
  • ✓
    Black hole
  • C
    Quasars
  • D
    Nebula
Answer
Correct option: B.
Black hole
It is well known that if the mass of the star is more than that of mass of Sun, it explodes after it's red giant stage and dies out giving rise to supernova and a black hole.
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MCQ 81 Mark
Albedo is maximum for
  • A
    Pluto
  • ✓
    Venus
  • C
    Earth
  • D
    Mercury
Answer
Correct option: B.
Venus
The albedo (reflection power) is maximum for Venus, because it reflects $85 \%$ of incident light. It's value of albedo is 0.85 .
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MCQ 91 Mark
The age of universe is believed to be
  • A
    $1$ billion years
  • B
    $ 10$ billion years
  • ✓
    $10-20$ billion years
  • D
    $ 1000$ billion years
Answer
Correct option: C.
$10-20$ billion years
The age of universe is believed to be 10-20 billion years.
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MCQ 101 Mark
The length of Milky way is
  • ✓
    (a) 100,000 light years
  • B
    (b) 10,000 light years
  • C
    (c) 1000 light years
  • D
    (d) 100 light years
Answer
Correct option: A.
(a) 100,000 light years
(a) Length of milky way is 10 light years.
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MCQ 111 Mark
Period of revolution increases in the order of
  • A
    Saturn, Uranus, Venus
  • ✓
    Mars, Saturn, Pluto
  • C
    Mercury, Neptune, Mars
  • D
    Mars, Jupiter, Venus
Answer
Correct option: B.
Mars, Saturn, Pluto
As $T^2 \propto r^3$ and distance of planet from sun in increasing order is for Mars, Saturn and Pluto.
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MCQ 121 Mark
Towards the centre of sun
  • A
    Density decreases
  • B
    Pressure decreases
  • C
    Temperature decreases
  • ✓
    Density and pressure increases
Answer
Correct option: D.
Density and pressure increases
As we move towards the centre of the sun, the density and pressure increases.
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MCQ 131 Mark
Hubble's law states that the velocity with which the 'milky way' is moving away from the earth is proportional to
  • A
    Square of the distance of the milky way from the earth
  • ✓
    Distance of milky way from the earth
  • C
    Mass of the milky way
  • D
    Product of the mass of the milky way and its distance from the earth
Answer
Correct option: B.
Distance of milky way from the earth
According to Hubble's law, $v \propto r$.
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MCQ 141 Mark
Milky way is
  • A
    A planet of our system
  • B
    A sun
  • C
    One of the solar system
  • ✓
    One of the enormous galaxies of universe
Answer
Correct option: D.
One of the enormous galaxies of universe
Milky way is one of the enormous galaxies of the universe.
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MCQ 151 Mark
Which of the following planets have rings around it
  • A
    Uranus
  • B
    Mars
  • C
    Jupiter
  • ✓
    Saturn
Answer
Correct option: D.
Saturn
Saturn only has ring around it.
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MCQ 161 Mark
Sun radiates continuously and maintains its brightness because
  • A
    Helium is converted into iron in its core
  • ✓
    Of fusion of hydrogen nuclei into helium
  • C
    Fusion of helium in hydrogen
  • D
    Burning of carbon, in its core
Answer
Correct option: B.
Of fusion of hydrogen nuclei into helium
The energy of the sun is due to fusion of hydrogen nuclei into helium.
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MCQ 171 Mark
There is no atmosphere on moon because
  • A
    There is no vegetation
  • ✓
    The escape velocity at its surface is very low
  • C
    Diffusion constant of gases is high
  • D
    There is vacuum in space
Answer
Correct option: B.
The escape velocity at its surface is very low
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MCQ 181 Mark
Venus appears brighter than other stars because
  • A
    It is heavier than other planets
  • B
    Its density is more than other planets
  • ✓
    It is nearer to earth in comparison to other planets
  • D
    Nuclear fusion takes place at its surface
Answer
Correct option: C.
It is nearer to earth in comparison to other planets
Venus appears brighter as it is nearest to the earth and the light of sun reflected form sun reaches earth with greater intensity.
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MCQ 191 Mark
A bright star is indicated to have a brightness magnitude of $-5$ compared to a star of brightness zero magnitude. It means that this star compared to the reference star of zero brightness is
  • A
    $100$ times less bright
  • B
    $5$ times more bright
  • C
    $5$ times less bright
  • ✓
    $ 100$ times more bright
Answer
Correct option: D.
$ 100$ times more bright
Given that magnitude for brightest star $=-5$ and magnitude of given star $=0$
Now $m-m=0-(-5)=5$
The brightness ratio is given by$\frac{l_1}{l_2}=100^{\left(m_2-m_1\right) / s}=100^{5 / 5}=100$
So bright star is 100 time bright that the dim star.
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MCQ 201 Mark
Mass of earth has been determined through
  • A
    Use of Kepler's $T / R$ constancy law
  • B
    Sampling the density of earth's crust and using $R$
  • ✓
    Cavendish's determination of $G$ and using $R$ and ' $g$ ' at the surface
  • D
    Use of periods of satellites at different heights above earth's surface
Answer
Correct option: C.
Cavendish's determination of $G$ and using $R$ and ' $g$ ' at the surface
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MCQ 211 Mark
A double star is a system of two stars rotating about their centre of mass only under their mutual gravitational attraction. Let the star have mass $m$ and $2 m$ and their separation be $l$. Their time period of rotation about their centre of mass will be proportional to
  • A
    $l^{2 / 3}$
  • B
    $1$
  • C
    $m^{1 / 2}$
  • ✓
    $m^{-1 / 2}$
Answer
Correct option: D.
$m^{-1 / 2}$
$\frac{G m \times 2 m}{l^2}=m \times \frac{2 l}{3} \frac{4 \pi^2}{T^2}$ or $T=\left(\frac{4 \pi^2 l^3}{3 G m}\right)^{1 / 2}$ i.e. $T \propto m^{-1 / 2}$
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MCQ 221 Mark
The wavelength of maximum energy, released during an atomic explosion, was $2.93 \times 10^{-} m$. Given that the Wien's constant is 2.93 $\times 10 mK$, the maximum temperature attained must be of the order of
  • A
    $10 K$
  • ✓
    $10 K$
  • C
    $10 K$
  • D
    $5.86 \times 10 K$
Answer
Correct option: B.
$10 K$
$\lambda_m T=b \Rightarrow 2.93 \times 10^{-10} \times T=2.93 \times 10^{-3} \Rightarrow T=10 \mathrm{~K}$
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MCQ 231 Mark
Hubble showed that the universe as a whole is expanding and the distant stars are receding from us. The spectral line from a star, when compared with the corresponding line from an source will then show
  • ✓
    A shift in frequency towards the red end
  • B
    A shift in frequency towards the violet end
  • C
    No shift in frequency at all
  • D
    A shift in frequency towards the violet end as well as a decrease in intensity
Answer
Correct option: A.
A shift in frequency towards the red end
When distant stars are receding from us, spectral line from the star, when compared to with the corresponding line from source will show red shift i.e. a shift in frequency towards the red end.
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MCQ 241 Mark
Asteroids are
  • ✓
    Small planets
  • B
    Shooting stars
  • C
    Found in a belt between Earth ad Venus
  • D
    None of these
Answer
Correct option: A.
Small planets
Asteroids are a group of rock pieces moving around the Sun in between Mars and Jupiter. They are believed to be the remains of a large planet which exploded due to gravitative attraction of Sun and that planet, may be called small planets.
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MCQ 251 Mark
In determining the temperature of a distant star, one makes use of
  • A
    Kirchhoff's law
  • B
    Stefan's law
  • ✓
    Wien's displacement law
  • D
    None of these
Answer
Correct option: C.
Wien's displacement law
The temperature of stars can be determined by Wiens displacement law which is $\lambda_m \cdot T=$ constant.
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MCQ 261 Mark
The motion of planets in the solar system is an example of conservation of
  • A
    Mass
  • B
    Momentum
  • ✓
    Angular momentum
  • D
    Kinetic energy
Answer
Correct option: C.
Angular momentum
The motion of planets in the solar system is based on the conservation of angular momentum.
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MCQ 271 Mark
Speed of recession of galaxy is proportional to it's distance
  • ✓
    Directly
  • B
    Inversely
  • C
    Exponentially
  • D
    None of these
Answer
Correct option: A.
Directly
Hubble's law state that. Speed of recession $(v) \propto$ distance $(r)$.
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MCQ 281 Mark
Great bear is a
  • A
    Star
  • B
    Galaxy
  • ✓
    Constellation
  • D
    Planet
Answer
Correct option: C.
Constellation
Great bear is a constellation, which is a group of some stars.
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MCQ 291 Mark
Surface temperature of the sun is of the order of
  • A
    $5000 K$
  • B
    $7000 K$
  • ✓
    $6000 K$
  • D
    $12000 K$
Answer
Correct option: C.
$6000 K$
Surface temperature of Sun is about $6000 \mathrm{~K}$.
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MCQ 301 Mark
A star which appears blue will be
  • A
    As hot as the sun
  • B
    Cooler than the sun
  • C
    Very cold indeed
  • ✓
    Much hotter than the sun
Answer
Correct option: D.
Much hotter than the sun
A star which appears blue will be much hotter than the sun.
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MCQ 311 Mark
Which of the following helps us in the determination of the temperature of sun
  • A
    Kirchhoff's law
  • B
    Maxwell Boltzmann law
  • C
    Planck's law
  • ✓
    Stefan's law
Answer
Correct option: D.
Stefan's law
According to Stefan's law $E=\sigma T^4$
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MCQ 321 Mark
Which of the following theories is the most satisfactory about the origin of the universe
  • ✓
    Big Bang theory
  • B
    Pulsating theory
  • C
    Steady state theory
  • D
    None of these
Answer
Correct option: A.
Big Bang theory
Big Bang theory is the most satisfactory theory about the origin of universe.
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MCQ 331 Mark
A study of binary stars is most helpful in
  • A
    Finding their distances
  • B
    Finding their temperature
  • C
    Finding their masses
  • ✓
    Verifying Newton's force law of gravitation
Answer
Correct option: D.
Verifying Newton's force law of gravitation
A study of binary star is most helpful in verifying Newton's law of gravitation.
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MCQ 341 Mark
Source of Sun's energy is
  • A
    Burning of hydrogen
  • B
    Fission reactions involving hydrogen
  • ✓
    Fusion reactions involving hydrogen
  • D
    Some other source
Answer
Correct option: C.
Fusion reactions involving hydrogen
Source of Sun's energy is fusion reactions involving hydrogen.
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MCQ 351 Mark
Which of the nine planets is nearest to sun
  • A
    Venus
  • ✓
    Mercury
  • C
    Mars
  • D
    Jupiter
Answer
Correct option: B.
Mercury
Mercury is the nearest planet to sun.
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MCQ 361 Mark
The hottest planet of solar system is
  • A
    Mars
  • ✓
    Mercury
  • C
    Venus
  • D
    Pluto
Answer
Correct option: B.
Mercury
The hottest planet of solar system is one which is nearest to sun and has no atmosphere.
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MCQ 371 Mark
In our solar system, there is one sun and
  • A
    Seven planets
  • ✓
    Nine planets
  • C
    Eleven planets
  • D
    Indefinite number of planets
Answer
Correct option: B.
Nine planets
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MCQ 381 Mark
Which of the planet is brightest
  • A
    Mercury
  • ✓
    Venus
  • C
    Mars
  • D
    Jupiter
Answer
Correct option: B.
Venus
Venus is the brightest planet.
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MCQ 391 Mark
Black hole is a
  • A
    Hole in the ozone layer of atmosphere
  • B
    Hole in earth's centre
  • ✓
    Highly dense matter available in the atmosphere
  • D
    Hole in troposphere
Answer
Correct option: C.
Highly dense matter available in the atmosphere
Black hole is highly dense malter in the atmosphere which has very large value of gravitational pull, so that nothing escapes from it.
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MCQ 401 Mark
According to modern astronomers into how many constellations, the whole sky is divided
  • A
    $10$
  • ✓
    $88$
  • C
    $880$
  • D
    $5000$
Answer
Correct option: B.
$88$
The sky is divided into $88$ constellations.
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MCQ 411 Mark
The sun revolves around the galaxy with a speed of $250 km / sec$ and it's radius is $3 \times 10$ light year. The mass of the milky way is
  • A
    (a) $3 \times 10^{-} kg$
  • ✓
    (b) $3 \times 10^{-} kg$
  • C
    (c) $5 \times 10^* kg$
  • D
    (d) $6 \times 10^{-} kg$
Answer
Correct option: B.
(b) $3 \times 10^{-} kg$
(b) The mass of galaxy is given by $M=\frac{v^2 r}{G}$ where $v=250 \mathrm{~km} / \mathrm{sec}=250 \times 10 \frac{\mathrm{m}}{\mathrm{sec}}$$\begin{aligned}& r=3 \times 10 l y=3 \times 10 \times 9.46 \times 10^{12} \mathrm{~km} \approx 3 \times 10^{20} \mathrm{~m} \\& \therefore m=\frac{\left(250 \times 10^3\right)^2 \times\left(3 \times 10^{20}\right)}{6.6 \times 10^{-11}} \approx 3 \times 10^{41} \mathrm{~kg} .\end{aligned}$
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MCQ 421 Mark
Which of the following is coldest planet
  • A
    Mercury
  • ✓
    Pluto
  • C
    Earth
  • D
    Venus
Answer
Correct option: B.
Pluto
Because pluto is farthest from Sun.
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MCQ 431 Mark
The colour of a star is an indication of its
  • A
    Weight
  • B
    Distance
  • ✓
    Surface temperature
  • D
    Size
Answer
Correct option: C.
Surface temperature
Surface temperature
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MCQ 441 Mark
A planet of mass $M$ has a satellite of mass $m$, revolving around the planet in a circular orbit of radius $r$ and time period $T$. The mass $(M)$ of the planet is
  • ✓
    $\frac{4 \pi^2 r^3}{G T^2}$
  • B
    $\frac{4 \pi^2 r^2}{G T^3}$
  • C
    $\frac{G T^2}{4 \pi r^3}$
  • D
    $\frac{r^3 G}{4 \pi T^2}$
Answer
Correct option: A.
$\frac{4 \pi^2 r^3}{G T^2}$
$F=\frac{G M m}{r^2}=m r \omega^2=m r\left(\frac{2 \pi}{T}\right)^2$
$ M=\frac{m r^3 4 \pi^2}{G m T^2}=\frac{4 \pi^2 r^3}{G T^2}$
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MCQ 451 Mark
An extremely hot star would appear to be
  • A
    Red
  • ✓
    Blue
  • C
    Yellow
  • D
    Orange
Answer
Correct option: B.
Blue
According to Wien's law, $\lambda_m \propto \frac{1}{T}$. It means higher the temperature of a star, the lower is the wavelength of maximum intensity radiation emitted from star which tells the colour of star.
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MCQ 461 Mark
The solar constant on the surface of the earth is $S$. What will be its value on the surface of another planet which is about $5.3$ A.L. away from sun
  • A
    $\frac{S}{5.3}$
  • ✓
    $\frac{S}{(5.3)^2}$
  • C
    $5.3 S$
  • D
    $(5.3): S$
Answer
Correct option: B.
$\frac{S}{(5.3)^2}$
Solar constant is the energy crossing per unit area per sec at earth's distance, area being normal to the sun's rays.
Also energy falling is inversely proportional to the square of distance from the source.
$\therefore S^{\prime}=\frac{S}{(5.3)^2}$
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MCQ 471 Mark
The condition for a uniform spherical mass $m$ of radius $r$ to be a black hole is [ $G=$ gravitational constant and $g=$ acceleration due to gravity]
  • A
    $(2 G m / r)^{1 / 2} \leq c$
  • B
    $(2 G m / r)^{1 / 2}=c$
  • ✓
    $(2 G m / r)^{1 / 2} \geq c$
  • D
    $(g m / r)^{1 / 2} \geq c$
Answer
Correct option: C.
$(2 G m / r)^{1 / 2} \geq c$
The criterion for a star to be black hole is$\frac{G M}{c^2 R} \geq \frac{1}{2} \text { or, } \sqrt{\frac{2 G M}{R}} \geq c .$
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MCQ 481 Mark
According to Hubble's law, the redshift $(Z)$ of a receding galaxy and its distance $r$ from earth are related as
  • ✓
    $Z \propto r$
  • B
    $Z \propto 1 / r$
  • C
    $Z \propto 1 / r^2$
  • D
    $Z \propto r^{3 / 2}$
Answer
Correct option: A.
$Z \propto r$
Hubble's law is a statement of a direct correlation between the distance $(r)$ to a galaxy and its recessional velocity as determined by the red shift $(Z)$. It is stated as $Z=H r$.
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MCQ 491 Mark
The difference in the lengths of a mean solar day and a sidereal day is about
  • A
    $1 min$
  • ✓
    $4 min$
  • C
    $15 min$
  • D
    $56 min$
Answer
Correct option: B.
$4 min$
The difference in the length of mean solar day and a sidereal day is about $4 \mathrm{~min}$.
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MCQ 501 Mark
Hubble's law is related with
  • A
    Comet
  • ✓
    Speed of galaxy
  • C
    Black hole
  • D
    Planetary motion
Answer
Correct option: B.
Speed of galaxy
Speed of galaxy is proportional to it's distance from us i.e. $U \propto r$. This is Hubble's law
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