Question

The number of ${Ag}^{+}$ ion in one drop of silver nitrate solution is:

• A. $2.12\times {10}^{20}$
• B. $7.2\times {10}^{20}$
• C. $7.2\times {10}^{21}$
• D. $7.2\times {10}^{19}$

Answer 1

Answer: (A)

$2.12\times {10}^{20}$

$1$ drop of $AgN{O}_3=12.5\times {10}^{-3}$ g ${Cl}^{-}$ (Given)

$1$ drop of $AgN{O}_3\equiv \frac{12.5\times {10}^{-3}}{35.5}$ mol ${Cl}^{-}$ $=3.52\times {10}^{-4}$ mol ${Cl}^{-}$

$=3.52\times {10}^{-4}$ mol $AgN{O}_3$

$=3.52\times {10}^{-4}$ mol ${Ag}^{+}$

$\equiv 3.52\times {10}^{-4}\times 6.023\times {10}^{23}$ ions of ${Ag}^{+}$ (as each mole has $N_A$ molecules)

$=2.12\times {10}^{20}$ ions of ${Ag}^{+}$

Hence, the correct option is $\text{A}$