Question

Acid rain takes place due to combination of acidic oxides with water and it is an envirronmental concern all over the world. Assuming rain water is uncontaminated with $HN{O}_3$ or $H_{2}S{O}_4$ and is in equilibrium with $1.25\times {10}^{-4}$atm $C{O}_2$, The Henry's law constant $\left(K_H\right)$ is $1.25\times {10}^6$ torr. $K_{a_1}$ of $H_{2}C{O}_3=4.3\times {10}^{-7}$.
Given: $K_{f}CuC{I}^{\oplus }=1.0(K_f$ is formation constant of $CuC{I}^{\oplus })$

If $S{O}_2$ content is the atmosphere is 0.64 ppm by volume, pH of rain water is (assume 100% ionisation of acid rain as monobasic acid).

• A. 4
• B. 5
• C. 6
• D. 7

Answer 1

The correct option is B 5

No of mole of $S{O}_2=\frac{0.64}{64}=0.01ppm=1\times {10}^{-5}M$

So $pH=-log\left[H^{+}\right]=5$ (as acid ionises 100%)