Auto Protolysis of Water

Q. 0.2 M solution of formic acid is ionized 3.2$\%$, its ionization constant is

1. $9.6\times {10}^{-3}$
2. $2.1\times {10}^{-4}$
3. $1.25\times {10}^{-6}$
4. $4.8\times {10}^{-5}$

Q. Which of the following expression is not true

1. $\left[H^{+}\right]<\sqrt{K_w}$ & $\left[O{H}^{-}\right]>\sqrt{K_w}$ for an alkaline solution
2. $\left[H^{+}\right]=\left[O{H}^{-}\right]=\sqrt{K_w}$ for a neutral solution at all temperatures.
3. $\left[H^{+}\right]=\left[O{H}^{-}\right]={10}^{-7}M$ for a neutral solution at all temperatures.
4. $\left[H^{+}\right]>\sqrt{K_w}$ & $\left[O{H}^{-}\right]<\sqrt{K_w}$ for an acidic solution

Q. Distilled water at ${80}^{\circ }C$ has hydronium ion $\left(H_3{O}^{+}\right)$ concentration equal to $1\times {10}^{-6}mol/L$.
The value of $K_w$ at this temperature would be:

1. $1\times {10}^{-9}$
2. $1\times {10}^{-14}$
3. $1\times {10}^{-12}$
4. $1\times {10}^{-6}$

Q. At ${25}^{\circ }C$ disociation constant of acid $HA$ and base $BOH$ in aqueous solution are same. The $pH$ of $0.01M$ solution of $HA$ is $5$. The $pOH$ of ${10}^{-4}$ M solution of $BOH$ at the same temperature is:

1. $3.5$
2. None of these
3. $4$
4. $6$

Q. The $p{K}_a$ value of acetic acid is 4.7447 at ${25}^{o}C.$ In what ratio of acetic acid and sodium acetate concentration is mixed to obtain a buffer with pH=4?
antilog(-0.7447)=0.18

1. 1:0.18
2. 1.8:1
3. 1:1.8
4. 0.18:1

Q. Autoprotolysis constant of $N{H}_3$ is

1. $\left[N{H}_4^{+}\right]\left[N{H}_3\right]$
2. $\left[N{H}_2^{-}\right]\left[N{H}_3\right]$
3. $\left[N{H}_4^{+}\right]\left[N{H}_2^{-}\right]$
4. $\frac{\left[N{H}_4^{+}\right]}{\left[N{H}_2^{-}\right]}$

Q. Autoprotolysis constant of $N{H}_3$ is

1. $\left[N{H}_4^{+}\right]\left[N{H}_2^{-}\right]$
2. $\frac{\left[N{H}_4^{+}\right]}{\left[N{H}_2^{-}\right]}$
3. $\left[N{H}_4^{+}\right]\left[N{H}_3\right]$
4. $\left[N{H}_2^{-}\right]\left[N{H}_3\right]$

Q. 10 mL of a strong acid solution of pH = 2.000 is mixed with 990 mL of another strong acid solution of pH = 4.000. What will be the pH of the resulting solution?
log1.99=0.3

1. 4.002
2. 3.7
3. 4.2
4. 4000

Q. The $pH$ of neutral water at ${25}^{\circ }\text{C}$ is $7.0$. What will be the nature of pure water at ${60}^{\circ }\text{C}$?

1. Acidic
2. Basic
3. Neutral
4. Cannot predict

Q. $K_{w}for{H}_{2}Ois9.62\times {10}^{-14}at{60}^{\circ }C$
The pH of water at this temperature is :

1. 6.5
2. 7.5
3. 7
4. 6