Question

The molecular mass of $HCl$ is:
A. $36.5$
B. $26.5$
C. $16.5$
D. $39.5$

Answer 1

Molecular mass is defined as the mass of the molecule and is measured in Daltons (Da or u or amu). It is to be noted that different molecules of the same compound can have different molecular mass due to difference in molecular mass of different isotopes.

Complete step by step answer:
Let’s start with discussing a little about the molecular mass for better understanding of the question. Molecular mass is defined as the mass of the molecule and is measured in Daltons (Da or u or amu). It is to be noted that different molecules of the same compound can have different molecular mass due to difference in molecular mass of different isotopes. Isotopes are the species which have the same amount of protons and electrons but different amounts of neutrons result in varying masses (example C-12 and C-14).
Coming back to the question, we are asked about the molecular mass of the molecule $HCl$. To find its molecular mass we need to know the atomic mass of Hydrogen $\left( H \right)$ and Chlorine $\left( {Cl} \right)$.
The atomic mass of the Hydrogen is $1$ and that of chlorine is $35.5$. The molecular mass of $HCl$ will simply be the sum of these two as only one-one atom of each is being used to make this molecule. So, the molecular mass of $HCl$ will be $1 + 35.5$ which will be equal to $36.5$.

So, the correct answer is Option A .

Note:
$HCl$ is a strong acid and it is also present inside our stomach. This acid helps us in digestion of food and inside our body, the $HCl$ is having a $pH$ of $1$ which is strong enough to burn our whole body. $HCl$ is being used in many reactions and hence it is always important to remember its molecular mass as we always need to prepare their molar solution for different-different experiments.