Conjugate Acids and Bases

Q.

Phenol Is Heated With Phthalic Anhydride In Presence Of Conc. ${\mathrm{H}}_2{\mathrm{SO}}_4$. The Product Gives Pink Colour With Alkali. The Product Is:

Q. In the dissociation of $N{H}_{4}OH$, if $N{H}_{4}Cl$ is added what will be the change in $pH$ for the $N{H}_{4}OH$ solution ?

1. Decreases
2. Increases
3. No change
4. first decreases and then increases.

Q. Strongest conjugate base is:

1. $C{l}^{-}$
2. $B{r}^{-}$
   
3. $F^{-}$
   
4. $I^{-}$

Q.

Which of the following is the strongest conjugate base

1. Cl^-

2. CH₃COO^-

3. SO₄^--

4. NO₂^-

Q. The conjugate acid of $N{H}_3$ is :

1. $N_2{H}_4$
2. $N{H}_2^{-}$
3. $N{H}_4^{+}$
4. $N{H}_{2}OH$

Q.

Assertion: Acidity of a base is due to the number of hydroxyl ions present in it.

Reason: Calcium hydroxide is a diacid base.

1. Both assertion and reason are correct and the reason is the correct explanation of the assertion.

2. Both assertion and reason are correct but the reason is not the correct explanation of the assertion.

3. The assertion is correct but the reason is incorrect

4. The assertion is incorrect but the reason is correct

Q. The strongest conjugate base is :

1. $N{O}_3^{-}$
2. $C{l}^{-}$
3. $S{O}_4^{2-}$
4. $C{H}_{3}CO{O}^{-}$

Q.

The degree of hydrolysis and pH of $0.1M$ sodium acetate solution are: Also calculate the concentration of all the ions at equilibrium. Hydrolysis constant of sodium acetate is $5.6\times {10}^{-10}$.

1. h = 7.5 x 10^-6, pH = 7.9

2. h = 8.5 x 10^-7, pH = 7.9

3. h = 7.5 x 10^-7 M, pH = 7.9

4. h = 8.5 x 10^-6, pH = 6.9

Q. The order of increasing acidic strength of $C{H}_4,N{H}_3,H_{2}O,HF$ is :

1. $C{H}_4<N{H}_3<H_{2}O<HF$
2. $HF<N{H}_3<H_{2}O<C{H}_4$
3. $HF<C{H}_4<H_{2}O<N{H}_3$
4. $N{H}_3<H_{2}O<C{H}_4<HF$

Q. The $p{K}_b$ for fluoride ion at ${25}^{\circ }C$ is $10.83$. The ionisation constant of hydrofluoric acid at this temperature is:
$antilog\overline{4}.83=6.76\times {10}^{-4}$

1. $1.74\times {10}^{-5}$
2. $3.52\times {10}^{-3}$
3. $6.76\times {10}^{-4}$
4. $5.38\times {10}^{-2}$

Q. With restpect to $N{H}_3$, Ammonium ion is

1. A conjugate acid
2. A conjugate base
3. Neither an acid nor a base
4. Both acid and base

Q. The strongest conjugate base is :

1. $N{O}_3^{-}$
2. $C{l}^{-}$
3. $S{O}_4^{2-}$
4. $C{H}_{3}CO{O}^{-}$

Q. Enthalpy of neutralization of the reaction between $C{H}_{3}COOH\left(aq\right)$ and $NaOH\left(aq\right)$ is -13.2 $kcale{q}^{-1}$ and that of the reaction between $H_{2}S{O}_4\left(aq\right)$ and $KOH\left(aq\right)$ is -13.7 $kcale{q}^{-1}$. The enthalpy of dissociation of $C{H}_{3}COOH\left(aq\right)$ is:

1. -0.5 $kcale{q}^{-1}$
2. +0.5 $kcale{q}^{-1}$
3. -26.9 $kcale{q}^{-1}$
4. +0.5 $kcale{q}^{-1}$

Q. The correct order of hydration energy of alkali is:

1. ${Rb}^{+}>K^{+}>{Na}^{+}>{Li}^{+}$
2. $K^{+}>{Rb}^{+}>{Na}^{+}>{Li}^{+}$
3. ${Li}^{+}>{Na}^{+}>K^{+}>{Rb}^{+}$
4. ${Na}^{+}>K^{+}>{Li}^{+}>{Rb}^{+}$

Q. Classify the following species into Lewis acids and Lewis bases and show how these act as Lewis acid/base: (a) ${OH}^{-}$ (b) $F^{-}$ (c) $H^{+}$ (d) ${BCl}_3$.

Q. Which of the following can be called as a conjugate acid - base pair?

1. $HCl,NaOH$
2. $H_3{O}^{+}/O{H}^{-}$
3. $H_{2}S{O}_4,HS{O}_4^{-}$
4. $H_{2}S/S^{2-}$

Q. $0.01M$ Solution of $H_{2}A$ has $pH=4$ . If $K_{a_1}$ for the acid is $4.45\times {10}^{-7}$ , the concentration of $H{A}^{-}$ ion in the solution would be :

1. $1.0\times {10}^{-2}M$
2. $4.45\times {10}^{-5}M$
3. $8.0\times {10}^{-5}M$
4. Unpredictable

Q. In the dissociation of $N{H}_{4}OH$, if $N{H}_{4}Cl$ is added what will be the change in $pH$ for the $N{H}_{4}OH$ solution ?

1. Decreases
2. Increases
3. No change
4. first decreases and then increases.

Q. Which of the following species act as an amphiprotic species in the following reactions?
$HCl\left(aq\right)+H_{2}O\left(aq\right)\rightleftharpoons H_3{O}^{+}\left(aq\right)+C{l}^{-}\left(aq\right)$

$N{H}_3\left(aq\right)+H_{2}O\left(aq\right)\rightleftharpoons N{H}_4^{+}\left(aq\right)+O{H}^{-}\left(aq\right)$

1. $N{H}_3$
2. $H_{2}O$
3. $O{H}^{-}$
4. $C{l}^{-}$

Q. The degree of ionization of a $0.1M$ bromoacetic acid solution is $0.132$. Calculate the $pH$ of the solution and the $p{K}_a$ of bromoacetic acid.

Q. The pH of a buffer is $4.745$. When $0.01mole$ of $NaOH$ is added to $1$ litre of it, the pH changes to $4.832$, calculate its buffer capacity.

Q. Why is $L{i}_{2}C{O}_3$ decomposed at a lower temperature whereas $N{a}_{2}C{O}_3$ at higher temperature?

Q. With restpect to $N{H}_3$, Ammonium ion is

1. A conjugate acid
2. A conjugate base
3. Neither an acid nor a base
4. Both acid and base

Q. The $p{K}_b$ for fluoride ion at ${25}^{\circ }C$ is $10.83$. The ionisation constant of hydrofluoric acid at this temperature is:
$antilog\overline{4}.83=6.76\times {10}^{-4}$

1. $1.74\times {10}^{-5}$
2. $3.52\times {10}^{-3}$
3. $6.76\times {10}^{-4}$
4. $5.38\times {10}^{-2}$

Q.

24. Ca(OH)₂ is an example of

1. monoacidic base

2. diacidic acid

3. triacidic base

4. strong base

Q. Among the following, the weakest conjugate base is :

1. $H^{-}$
2. $C{H}_3^{-}$
3. $C{H}_3{O}^{-}$
4. $C{l}^{-}$

Q. Among the following, the weakest conjugate base is :

1. $H^{-}$
2. $C{H}_3^{-}$
3. $C{H}_3{O}^{-}$
4. $C{l}^{-}$

Q. The $pH$ of 0.1 M solution of cyanic acid ($HCNO$) is 2.34. Calculate the ionization constant of the acid and its degree of ionization in the solution.

Q. Consider various species generated when $H_{3}P{O}_4$ is dissolved in water. According to the Bronsted Lowry’s Concept among these, the conjugate acid of $HP{O}_4^{2-}$ is :

1. $HP{O}_4^{2-}$
2. $H_{2}P{O}_4^{-}$
3. $P{O}_4^{3-}$
4. $H_3{O}^{+}$

Q.

Which of the following is the strongest conjugate base

1. $C{l}^{-}$

2. $C{H}_{3}CO{O}^{-}$

3. $S{O}_4^{2-}$

4. $N{O}_2^{-}$