MCQ 11 Mark
The anion of an element has:
- ✓
More electrons than the normal atom.
- B
Less electrons than the normal atom.
- C
More protons than the normal atom.
- D
Same number of electrons as normal atom.
AnswerCorrect option: A. More electrons than the normal atom.
The anion of an element has more electrons than the normal atom because it is formed by gaining electrons.
View full question & answer→MCQ 21 Mark
In hydrogen peroxide $ (H_2O_2),$ the proportion of hydrogen and oxygen by mass is:
- A
$1 : 8$
- B
$1 : 16$
- C
$8 : 1$
- ✓
$16 : 1$
AnswerCorrect option: D. $16 : 1$
In hydrogen peroxide, the ratio of hydrogen to oxygen is $1 : 16$ by mass.
View full question & answer→MCQ 31 Mark
The element having atomicity ‘four’ is most likely to be:
AnswerPhosphorus has an atomicity of $4.$
View full question & answer→MCQ 41 Mark
The Latin language name of an element is natrium. The English name of this element is:
AnswerThe English name of the element natrium is Sodium(Na).
View full question & answer→MCQ 51 Mark
The atoms of which of the following pair of elements are most likely to exist in free state?
AnswerAtoms of helium and neon exist in a free state because they are inert gases and chemically inactive.
View full question & answer→MCQ 61 Mark
The law of constant proportions was given by:
AnswerThe law of constant proportion was proposed by Joseph Proust.
View full question & answer→MCQ 71 Mark
An element which can exhibit valencies of $2, 4$ and $6$ can be:
AnswerSulphur exhibits the valencies of $2, 4$ and $6.$
View full question & answer→MCQ 81 Mark
If $1.4g$ of calcium oxide is formed by the complete decomposition of calcium carbonate, then the amount of calcium carbonate taken and the amount of carbon dioxide formed will be respectively:
- A
$2.2g$ and $1.1g$
- ✓
$1.1g$ and $2.5g$
- C
$2.5g$ and $1.1g$
- D
$5.0g$ and $1.1g$
AnswerCorrect option: B. $1.1g$ and $2.5g$
Molecular mass of $\ce{CaCO_3}: 40 + 12 + (16 \times 3) = 100g$
Molecular mass of $\ce{CaO}: 40 + 16 = 56g$
Molecular mass of $\ce{CO_2}: 12 + (16 \times 2) = 44g$
Reaction for the decomposition of calcium carbonate:
$\text{CaCO}_3\xrightarrow{\ \ \ \ \ \ \ \ \ \ \ \ \ }\text{CaO}\ +\ \text{CO}_2\\ \ \ 100\text{g} \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 56\text{g}\ \ \ \ \ \ \ \ 44\text{g}\\\ \ \ \ \text{X}\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 1.4\text{g}\ \ \ \ \ \ \ \ \ \text{Y}$
$56g$ of $\ce{CaO}$ is obtained when $100g$ of $\ce{CaCO_3}$ is burnt.
Therefore, to get $1.4g$ of $\ce{CaO,}$ the amount of $\ce{CaCO_3}$ to be burnt will be $\frac{100\ \times\ 1.4}{56}=2.5\text{g}$
For $\ce{CO_2,}$
$100g$ of $\ce{CaCO_3}$ yields $44g$ of $\ce{CO_2}$
Therefore, $2.5g$ of $\ce{CaCO_3}$ will yield $\frac{44\ \times\ 2.5}{100}=1.1\text{g}$
View full question & answer→MCQ 91 Mark
One $nm$ is equal to:
- A
$10^{-9} \mathrm{~mm}$.
- ✓
$10^{-7} \mathrm{~cm}$.
- C
$10^{-9} \mathrm{~cm}$.
- D
$10^{-6} \mathrm{~m}$.
AnswerCorrect option: B. $10^{-7} \mathrm{~cm}$.
One nanometre is equal to $10^{-7}$ centimetre.
View full question & answer→MCQ 101 Mark
Two elements $X$ and $Y$ have valencies of $5$ and $3,$ and $3$ and $2,$ respectively. The elements $X$ and $Y$ are most likely to be respectively:
AnswerElements $X$ and $Y,$ most likely, are nitrogen and iron.
View full question & answer→MCQ 111 Mark
In water, the proportion of oxygen and hydrogen by mass is:
- A
$1 : 4$
- B
$1 : 8$
- C
$4 : 1$
- ✓
$8 : 1$
AnswerCorrect option: D. $8 : 1$
In water, the ratio of oxygen to hydrogen is $8 : 1$ by mass.
View full question & answer→MCQ 121 Mark
The atomicities of ozone, sulphur, phosphorus and argon are respectively:
- A
$8, 3, 4$ and $1$
- B
$1, 3, 4$ and $8$
- C
$4, 1, 8$ and $3$
- ✓
$3, 8, 4$ and $1$
AnswerCorrect option: D. $3, 8, 4$ and $1$
The atomicity of ozone$(O_3)$ is $3,$ sulphur$(S)- 8,$ phosphorus$(P)- 4,$ Argon$($noble gas, $Ar)- 1.$
View full question & answer→MCQ 131 Mark
Which of the following represents a correct chemical formula$?$
- A
$CaCl$
- ✓
$Na_3N$
- C
$NaSO_4$
- D
$NaS$
AnswerCorrect option: B. $Na_3N$
The correct chemical formula among the listed chemicals is of $Na_3N$.
View full question & answer→MCQ 141 Mark
If $12$ gram of carbon has $x$ atoms, then the number of atoms in $12$ grams of magnesium will be:
- A
$x$
- B
$2x$
- ✓
$\frac{\text{x}}{2}$
- D
$1.5x$
AnswerCorrect option: C. $\frac{\text{x}}{2}$
The number of atoms in $12g$ of magnesium will be $\frac{\text{x}}{2}$
View full question & answer→MCQ 151 Mark
The number of electrons in an ion $Y^{2+}$ is $10$. The atomic number of element $Y$ is most likely to be:
AnswerThe atomic number of element $Y$ would be $12.$
View full question & answer→MCQ 161 Mark
The law of constant phosphorus, sulphur and krypton, the elements having the lowest and highest atomicities are respectively:
AnswerOut of ozone, phosphorus, sulphur and krypton, krypton has the lowest atomicity and sulphur the highest .
View full question & answer→MCQ 171 Mark
Which of the following correctly represents $360g$ water$?$
- $2$ moles of $H_2O.$
- $20$ moles 0f water.
- $6.022 \times 10^{23}$ molecules of water.
- $1.2044 \times 10^{25} $molecules of water.
- A
$(i)$
- B
$(i)$ and $(iv)$
- C
$(ii)$ and $(iii)$
- ✓
$(ii)$ and $(iv)$
AnswerCorrect option: D. $(ii)$ and $(iv)$
$20$ moles of water and $1.2044 \times 10^{25}$ molecules of water correctly represent $360$ gms of water.
View full question & answer→MCQ 181 Mark
An ionic compound will be formed by the combination of one of the following pairs of elements. This pair of elements is:
AnswerChlorine and calcium can form an ionic compound $\text{CaCl}_2$.
View full question & answer→MCQ 191 Mark
A student wants to have $3.011 \times 10^{23}$ atoms each of magnesium and carbon elements. For this purpose, he will have to weigh:
- A
$24g$ of magnesium and $6g$ of carbon.
- B
$12g$ of carbon and $24g$ of magnesium.
- C
$20g$ of magnesium and $10g$ of carbon.
- ✓
$12g$ of magnesium and $6g$ of carbon.
AnswerCorrect option: D. $12g$ of magnesium and $6g$ of carbon.
The student will have to weigh $12g$ of Magnesium and $6g$ of Carbon.
View full question & answer→MCQ 201 Mark
The scientist who proposed the first letter (or first letter and another letter) of the Latin or English name of an element as its symbol, was:
AnswerBerzelius proposed the first letter (or first letter and another letter) of the Latin or English name of any element as its symbol.
View full question & answer→MCQ 211 Mark
The English name of an element is potassium, its Latin name will be:
AnswerThe Latin name of the element potassium is kalium. Hence, the symbol for potassium is $K.$
View full question & answer→MCQ 221 Mark
The atomic number of an element $X$ is $13.$ What will be the number of electrons in its ion $X^{3+}$?
AnswerIf the atomic number of $X$ is $13,$ the number of electrons in its $X^{3+}$ ion would be $13 - 3 = 10.$
View full question & answer→MCQ 231 Mark
Which of the following pair of elements represents a mole ratio of $1 : 1?$
- A
$10g$ of calcium and $12g$ of magnesium.
- ✓
$12g$ of magnesium and $6g$ of carbon.
- C
$12g$ of carbon and $20g$ of calcium.
- D
$20g$ of sodium and $20g$ of calcium.
AnswerCorrect option: B. $12g$ of magnesium and $6g$ of carbon.
$12g$ of magnesium and $6g$ of carbon will have a mole ratio of $1 : 1$
View full question & answer→MCQ 241 Mark
The atomic theory of matter was proposed by:
AnswerThe atomic theory of matter was proposed by John Dalton.
View full question & answer→MCQ 251 Mark
If $32g$ of sulphur has $x$ atoms, then the number of atoms in $32g$ of oxygen will be:
- A
$\frac{\text{x}}{2}$
- ✓
$2x$
- C
$x$
- D
$4x$
AnswerThe number of oxygen atoms in $32g$ of oxygen will be $2x.$
View full question & answer→MCQ 261 Mark
If the number of electrons in an ion $Z^{3-}$ is $10,$ the atomic number of element $Z$ will be:
AnswerIf the number of electrons in an ion $Z^{3-}$ is $10$ , the atomic number of element $Z$ will be $7$ because the ion is formed by gaining three electrons.
View full question & answer→MCQ 271 Mark
The formula of the sulphate of an element $X$ is $\mathrm{X}_2\left(\mathrm{SO}_4\right)_3$. The formula of nitride of element $X$ will be:
AnswerFormula of nitride of the element $X$ will be $XN.$
View full question & answer→MCQ 281 Mark
The ratio of moles of atoms in $12g$ of magnesium and $16g$ of sulphur will be:
- A
$3 : 4$
- B
$4 : 3$
- ✓
$1 : 1$
- D
$1 : 2$
AnswerCorrect option: C. $1 : 1$
The ratio of moles of atoms in $12g$ of Magnesium and $16g$ of Sulphur will be $1 : 1$
View full question & answer→MCQ 291 Mark
A particle $P$ has $18$ electrons, $20$ neutrons and $19$ protons. This particle must be:
AnswerParticle $P$ must be a cation.
View full question & answer→MCQ 301 Mark
Molecular compounds are usually formed by the combination between:
- A
- ✓
Two different non-metals.
- C
- D
Any two gaseous elements.
AnswerCorrect option: B. Two different non-metals.
Molecular compounds are formed by the combination of two different non-metals.
View full question & answer→MCQ 311 Mark
The law of conservation of mass was given by:
AnswerThe law of conservation of mass was given by Lavoisier.
View full question & answer→MCQ 321 Mark
The atomic number of an element $E$ is $16.$ The number of electrons in ion $E^{2-}$ will be:
AnswerElement with an atomic number $16$ will have $18$ electrons in its $E^{2-}$ ion because anions are formed by gaining electrons.
View full question & answer→MCQ 331 Mark
Which of the following elements has the same molecular mass as its atomic mass?
AnswerNeon’s molecular mass is equivalent to its atomic mass.
View full question & answer→MCQ 341 Mark
The formula of a compound is $X_3Y$. The valencies of elements $X$ and $Y$ will be respectively:
- ✓
$1$ and $3$
- B
$3$ and $1$
- C
$2$ and $3$
- D
$3$ and $2$
AnswerCorrect option: A. $1$ and $3$
Valencies of element $X$ and $Y$ will be $1$ and $3,$ respectively.
View full question & answer→MCQ 351 Mark
The symbols of the elements cobalt, aluminium, helium and sodium respectively written by a student are as follows. Which symbol is the correct one$?$
AnswerThe correct symbols of cobalt, aluminium, and sodium are $Co, Al$ and $Na$ respectively.
View full question & answer→MCQ 361 Mark
One of the following elements has an atomicity of ‘one’. This element is:
AnswerThe atomicity of Helium$(He)$ is $1.$
View full question & answer→MCQ 371 Mark
The symbol of a metal element which is used in making thermometers is:
AnswerThe symbol of the metal used in making thermometers is $Hg($Mercury$).$
View full question & answer→MCQ 381 Mark
Which of the following has the maximum number of atoms$?$
- A
$18\ g$ of $\mathrm{H}_2 \mathrm{O}$
- B
$18\ g$ of $\mathrm{O}_2$
- C
$18\ g$ of $\mathrm{CO}_2$
- ✓
$18\ g$ of $\mathrm{CH}_4$
AnswerCorrect option: D. $18\ g$ of $\mathrm{CH}_4$
$18\ g$ of $\mathrm{CH}_4$ has maximum number of atoms.
View full question & answer→MCQ 391 Mark
The cation of an element has:
- A
The same number of electrons as its neutral atom.
- B
More electrons than a neutral atom.
- C
Less protons than a neutral atom.
- ✓
Less electrons than a neutral atom.
AnswerCorrect option: D. Less electrons than a neutral atom.
The cation of an element has less electrons than a neutral atom.
View full question & answer→MCQ 401 Mark
A particle $X$ has $17$ protons, $18$ neutrons and $18$ electrons. This particle is most likely to be:
Answer$X,$ most likely, is an anion because the number of electrons is more than the number of protons.
View full question & answer→