Question

An iodised salt contain 0.5% of $NaI$. A person consumes $3g$ of salt everyday. The number of iodide ions going into his body everyday is:

[Atomic wt. of Iodine = 127]

• A. ${10}^{-4}$
• B. $6.02\times {10}^{-4}$
• C. $6.023\times {10}^{19}$
• D. $6.02\times {10}^{23}$

Answer 1

Answer: (C)

$6.023\times {10}^{19}$

$3$ gm of salt corresponds to $3\times \frac{0.5}{100}=0.015$ gm of $NaI$

or

$\frac{0.015}{127+23}=1.0\times {10}^{-4}$ moles of $NaI$.

This is also equal to the number of moles of iodide ions.

The number of iodide ions going into his body everyday is $1.0\times {10}^{-4}\times 6.023\times {10}^{23}=6.023\times {10}^{19}$.