Question

Calculate number of neutrons present in $12\times {10}^{25}$ atoms of oxygen ${(}_8{O}^{17})$:
(Given : N${}_A=6\times {10}^{23}$)

• A. $1800$
• B. $1600$
• C. $1800N_A$
• D. $3200N_A$

Answer 1

The correct option is C $1800N_A$

Atomic number =$P=8$

Atomic Mass =$N+P=17$

$N=9$

Total no. of Neutrons = $9\times 12\times {10}^{25}$

=$\frac{9\times 12\times {10}^{25}\times N_A}{6\times {10}^{23}}$

$=1800N_A$

Hence, the correct option is C.