Question

The molecular mass of ${\text{NaHCO}}_3$ is

• A. 66 u
• B. 84 u
• C. 107 u
• D. 100 u

Answer 1

The correct option is B

84 u

Molecular mass of any molecule is equal to the sum of the masses of its constituent atoms.
Atomic mass of hydrogen = 1 u
Atomic mass of sodium = 23 u
Atomic mass of carbon = 12 u
Atomic mass of oxygen = 16 u

Therefore, the molecular mass of $NaH{CO}_3$
= $1\times Atomicmassofsodium+1\times Atomicmassofhydrogen+1\times Atomicmassofcarbon+3\times Atomicmassofoxygen$

= $1\times 23+1\times 1+1\times 12+3\times 16$
= 23 + 1 + 12 + 48
= 84 u