Question

The number of molecules in $1.7$ gram of ammonia will be:

• A. $0.1$
• B. $6.02\times {10}^{23}$
• C. $6.02\times {10}^{22}$
• D. $3.02\times {10}^{23}$

Answer 1

Answer: (C)

$6.02\times {10}^{22}$

1.7 gram of ammonia (molecular weight 17 g/mol) $=\frac{1.7g}{17g/mol}=0.1mol$.
The number of molecules in 1.7 gram of ammonia $=0.1mol\times 6.02\times {10}^{23}molecules/mol=6.02\times {10}^{22}molecules$