9
MCQ (Single Correct Answer)
What is the mass per cent of carbon in carbon dioxide?
A
$0.034 \%$
B
$27.27 \%$
C
$3.4 \%$
D
$28.7 \%$
10
MCQ (Single Correct Answer)
The empirical formula and molecular mass of a compound are $\mathrm{CH}_2 \mathrm{O}$ and 180 g respectively. What will be the molecular formula of the compound?
A
$\mathrm{C}_9 \mathrm{H}_{18} \mathrm{O}_9$
B
$\mathrm{CH}_2 \mathrm{O}$
C
$\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6$
D
$\mathrm{C}_2 \mathrm{H}_4 \mathrm{O}_2$
11
MCQ (Single Correct Answer)
If the density of a solution is $3.12 \mathrm{~g} \mathrm{~mL}^{-1}$, the mass of 1.5 mL solution in significant figures is ............. .
A
4.7 g
B
$4680 \times 10^{-3} \mathrm{~g}$
C
4.680 g
D
46.80 g
12
MCQ (Single Correct Answer)
Which of the following statements about a compound is incorrect?
A
A molecule of a compound has atoms of different elements
B
A compound cannot be separated into its constituent elements by physical methods of separation
C
A compound retains the physical properties of its constituent elements
D
The ratio of atoms of different elements in a compound is fixed
13
MCQ (Single Correct Answer)
Which of the following statements is correct about the reaction given below?
$$4 \mathrm{Fe}(s)+3 \mathrm{O}_2(\mathrm{~g}) \longrightarrow 2 \mathrm{Fe}_2 \mathrm{O}_3(\mathrm{~g})$$
A
Total mass of iron and oxygen in reactants $=$ total mass of iron and oxygen in product therefore it follows law of conservation of mass
B
Total mass of reactants $=$ total mass of product, therefore, law of multiple proportions is followed
C
Amount of $\mathrm{Fe}_2 \mathrm{O}_3$ can be increased by taking any one of the reactants (iron or oxygen) in excess
D
Amount of $\mathrm{Fe}_2 \mathrm{O}_3$ produced will decrease if the amount of any one of the reactants (iron or oxygen) is taken in excess