Factors Affecting Alpha

Q.

Electrolytes when dissolved in water dissociate into their constituent ions.

The degree of dissociation of an electrolyte increases with

1. Increasing concentration of the electrolyte

2. Decreasing concentration of the electrolyte

3. Decreasing temperature

4. Presence of a substance yielding a common ion

Q.

$NaOH$ is a strong base because

1. It gives $O{H}^{-}$ ion.

2. It can be oxidised

3. It can be easily ionised

4. It provides $H_3{O}^{+}$ ions.

Q.

How many gram moles of $HCl$ will be required to prepare one litre of a buffer solution (containing $NaCN$ and $HCN$) of $pH8.5$ using $0.01gram$ formula weight of $NaCN$ ?

$K_a\left(HCN\right)$ = $4.1\times {10}^{-10}$

1. 

2. 

3. 

4. 

Q.

The extent of ionization increases

1. With the increase in concentration of solute

2. On addition of excess water to solution

3. On decreasing the temperature of solution

4. On stirring the solution vigorously

Q.

In the purification of NaCl, impure solution is saturated with HCl gas. The principle involved is

1. Common ion effect and low solubility of MgCl₂ and CaCl₂ when compared to NaCl

2. Common ion effect and high solubility of MgCl₂ and CaCl₂ when compared to NaCl

3. K_SP of NaCl is greater than that of MgCl₂

4. K_SP of NaCl is greter than that of CaCl₂ but less than that of MgCl₂

Q. 0.2(M) solution of monobasic acid is dissociated to $0.95\%$ calculate its dissociation constant.
C = 0.2 M

1. $1.6\times {10}^{-4}$
2. $1.8\times {10}^{-5}$
3. $2\times {10}^{-4}$
4. $1.7\times {10}^{-5}$

Q.

Ammonium hydroxide is a weak base because

1. It has low vapour pressure

2. It is only slightly ionized

3. It is not a hydroxide of any metal

4. It has low density

Q. $0.02M$ solution of $H_{2}A$ has $pH=4$. If $K_{a_1}$ for the acid is $5\times {10}^{-7}M$, the concentration of $H{A}^{-}$ ion in the solution would be :

1. $2\times {10}^{-7}M$
2. $1\times {10}^{-6}M$
3. $3\times {10}^{-5}M$
4. $1\times {10}^{-4}M$

Q.

Electrolytes when dissolved in water dissociate into their constituent ions.

The degree of dissociation of an electrolyte increases with

1. Increasing concentration of the electrolyte

2. Decreasing concentration of the electrolyte

3. Decreasing temperature

4. Presence of a substance yielding a common ion

Q. The degree of dissociation of $PC{l}_5$ at a certain temperature and pressure= $1atm$ is 0.20. Calculate the value of equilibrium constant $K_p$.

1. $0.084$ atm
2. $0.84$ atm
3. $0.42$ atm
4. $0.042$ atm

Q. The dissociation constant of $0.05MC{H}_{3}COOH$ is given as $1.8\times {10}^{-5}$. Calculate the percentage dissociation of $C{H}_{3}COOH$ in $0.2MHCl$ solution.

1. $1.5\times {10}^{-6}M$
2. $9\times {10}^{-3}M$
3. $1.8\times {10}^{-4}M$
4. $6.8\times {10}^{-5}M$

Q.

An ionizing solvent has

1. Low value of dielectric constant

2. High value of dielectric constant

3. A dielectric constant equal to 1

4. Has a high melting point

Q.

0.1 mole of $C{H}_{3}N{H}_2(K_b=5\times {10}^{-4}$ is mixed with 0.08 mole of $HCl$ and

diluted to one litre. What will be the $H^{+}$ concentration in the solution?

1. 8 x 10^-2 M

2. 8 x 10^-11 M

3. 1.6 x 10^-11 M

4. 8 x 10^-5 M

Q. Find the dissociation constant $K_a$ of a weak monobasic acid which is 3.5% dissociated in a $\frac{M}{10}$ solution at ${25}^{\circ }C$

1. $0.5\times {10}^{-3}$
2. $2.62\times {10}^{-6}$
3. $4.2\times {10}^{-6}$
4. $1.27\times {10}^{-4}$

Q. The pH of $0.05M$ aqueous solution of diethyl amine is 12.0. Calculate $K_b$.

1. $2.5\times {10}^{-3}$
2. $2.5\times {10}^{-4}$
3. $5\times {10}^{-3}$
4. $5\times {10}^{-4}$

Q. is normality of solution equals to normality of h+ion when hcl and h2so4 are mixed

Q. Which of the following statements is/are correct about the ionic product of water?

1. At 298K , Equilibrium constant of water < ionic product of water
   i.e. $K_c<K_w$
2. $K_w$ at 373 K $>K_w$ at 298 K
3. Ionic product of water at ${25}^{\circ }C$ is ${10}^{-14}$
4. None of the above.

Q. $0.02M$ solution of $H_{2}A$ has $pH=4$. If $K_{a_1}$ for the acid is $5\times {10}^{-7}M$, the concentration of $H{A}^{-}$ ion in the solution would be :

1. $2\times {10}^{-7}M$
2. $1\times {10}^{-6}M$
3. $3\times {10}^{-5}M$
4. $1\times {10}^{-4}M$

Q. The dissociation constants of two weak bases $AOH$ and $BOH$ are $K_{b_1}=1\times {10}^{-8}$ and $K_{b_2}=2\times {10}^{-9}$ respectively. The $H^{+}$ ions concentration of the solution that is simultaneously 0.01 M in $AOH$ and 0.05 M in $BOH$ at ${25}^{\circ }C$ is:

1. $1.41\times {10}^{-5}M$
2. $7.07\times {10}^{-10}M$
3. $9.5\times {10}^{-12}M$
4. $4\times {10}^{-6}M$

Q. The concentration of formate ion $\left(HCO{O}^{-}\right)$ present in 0.1 M formic acid $\left(HCOOH\right)$ solution at equilibrium is :
$(K_a=1.6\times {10}^{-4})$

1. $4\times {10}^{-3}M$
2. $3\times {10}^{-6}M$
3. $1.5\times {10}^{-3}M$
4. $5\times {10}^{-6}M$

Q. The $\left[H^{+}\right]$ of the resulting solution that is 0.01 M in acetic acid $(K_a=1.8\times {10}^{-5}M)$ and 0.01 M in benzoic acid. $(K_a=6.3\times {10}^{-5}M)$ will be:

1. $4\times {10}^{-4}M$
2. $16\times {10}^{-4}M$
3. $81\times {10}^{-4}M$
4. $9\times {10}^{-4}M$

Q. 68. In an acidic solution , Iˉ changes to I₂ . How many grams of I₂ are produced if , in the same process , 1.5 x10²² electrons are used upto reduce AsO₄ˉˉˉ and AsO₃ˉˉˉ ?

Q.

define common ion effect. how does it effect the solubility of electrolytes.

Q. 41.A hydrogen electrode placed in buffer solution of CH3COONA and CH3COONA in the molar ratio c1:c2 and c2:c1 has oxidation potential E1 and E2 volts respectively at 298K(pH2=1atm).The Pka value of acetic acid will given by

Q. Assertion:
(A)$\to$When water is heated to ${80}^{\circ }C$ then concentrations $\left[H^{+}\right]and\left[O{H}^{-}\right]$ will increase.
Reason:
(R)$\to K_w$ increases with decrease in temperature.

1. Both, A and R, are true and R is the correct explanation of A
2. Both, A and R, are true but R is not the correct explanation of A
3. A is true but R is false
4. Both A and R are false

Q. $H_{3}A$ is a weak triprotic acid $(K{a}_1={10}^{-5},K{a}_2={10}^{-9},K{a}_3={10}^{-13}).$
What is the value of $pX$ of $0.1M{H}_{3}A\left(aq\right)$ solution?
Given $pX=-logX$ and $X=\frac{\left[A^{3-}\right]}{\left[H{A}^{2-}\right]}$.

1. 7
2. 8
3. 9
4. 10

Q. Given an aqueous solution of $0.034M$ carbonic acid, the ionization constants for carbonic acid are $K_1=4.2\times {10}^{-7}$ and $K_2=4.8\times {10}^{-11}$
Select the correct statement from the following:

1. The concentration of $C{O}_3^{2-}$ is $0.034M$.
2. The concentration of $C{O}_3^{2-}$ is greater than that of $HC{O}_3^{-}$.
3. The concentration of $H^{+}$ and $HC{O}_3^{-}$ are approximately equal.
4. The concentration of $H^{+}$ is double that of $C{O}_3^{2-}$.

Q. Calculate the ratio $\frac{{\alpha }_1}{{\alpha }_2}$ of a solution obtained by mixing equal volume of 0.02 M $HOCl$ ( a weak acid) and 0.2 M $C{H}_{3}COOH$ solution.
where,
${\alpha }_1$ is the degree of dissociation of $HOCl$
${\alpha }_2$ is the degree of dissociation of $C{H}_{3}COOH$
Given that:
$K_{a_1}\left(HOCl\right)=2\times {10}^{-7}$
$K_{a_1}\left(C{H}_{3}COOH\right)=2\times {10}^{-5}$

1. 0.2
2. 0.02
3. 0.01
4. 0.5

Q. Calculate the equilibrium concentration of $B^{+}$ ions in a solution obtained by mixing equal volume of 0.02 M $AOH$ and 0.2 M $BOH$ solution.

Given that,
$K_b\left(AOH\right)=1\times {10}^{-8}$
$K_b\left(BOH\right)=2\times {10}^{-9}$

1. $1.16\times {10}^{-5}M$
2. $6\times {10}^{-8}M$
3. $4.55\times {10}^{-3}M$
4. $3\times {10}^{-8}M$

Q. Given that, $K_{a_1}=1.0\times {10}^{-7}$ and $K_{a_2}=1.3\times {10}^{-13}$ for $H_{2}S$.
Find the concentration of $S^{2-}$ and $H{S}^{-}$ ions (in $mol/L$) respectively in the solution consisting of $0.1M{H}_{2}S$ and $0.5MHCl$.

1. $5.2\times {10}^{-21}$ and $2\times {10}^{-8}$
2. $1.0\times {10}^{-18}$ and $2.3\times {10}^{-6}$
3. $6.5\times {10}^{-19}$ and $1.3\times {10}^{-7}$
4. $4.6\times {10}^{-20}$ and $1.3\times {10}^{-8}$