Question

Molecular mass of nitric acid is:
A: $22u$
B: $12u$
C: $33u$
D: $63u$

Answer 1

Hint : The molecular or molar mass of any chemical compound refers to the ratio of mass of a sample of that particular compound and the amount of substance in that particular sample (in moles). The molar mass is actually a bulk characteristic of a substance rather than molecular. The molar mass is generally represented as $gmo{l^{ - 1}}$ .

Complete Step By Step Answer:
The molecular mass of any compound can be found out by adding the relative atomic masses of each element present in that particular compound. The number of atoms in a compound can be determined from their chemical formula.
Now, let us calculate the molecular mass of the given compound i.e. nitric acid. The chemical formula of nitric acid is $HN{O_3}$ . We already know the atomic masses of hydrogen, nitrogen and oxygen as stated below:
$H = 1u$
$N = 14u$
$O = 16u$
From the chemical formula, it is clear that nitric acid contains one atom of hydrogen, one atom of nitrogen and three atoms of oxygen and thus molecular mass of this compound can be calculated by adding the mass of one hydrogen atom, one nitrogen atom and three oxygen atoms as shown below:
$Molecular{\text{ }}mass{\text{ }}of{\text{ }}HN{O_3} = (1 \times H) + (1 \times N) + (3 \times O) = (1 \times 1) + (1 \times 14) + (3 \times 16) = 63u$
Hence, the correct answer is Option D.

Note :
Molecular mass plays a significant role in chemistry especially during setting up an experiment. During testing principles which involve specific amounts or quantities of a substance, molecular mass is used to figure out the exact quantity to be weighed of that particular substance. Basically molecular mass is used to determine the stoichiometry in the chemical reactions as well as equations.