Degree of Dissociation

Q. Consider a weak electrolyte, $A{B}_3$ having a concentration of 0.1 M in solution. If the degree of dissociation is 0.2, Calculate the ionisation constant $K_i$ of $A{B}_3$.

1. $2.4\times {10}^{-9}$
2. $1.4\times {10}^{-2}$
3. $3.4\times {10}^{-7}$
4. $5.4\times {10}^{-5}$

Q. The percentage degree of dissociation of $0.05M$ acetic acid $\left(C{H}_{3}COOH\right)$ solution with $K_a=1.8\times {10}^{-5}$ is :

1. 0.55
2. 5.5
3. 1.9
4. 19

Q. Consider a weak base, $BOH$. Molar concentration of $BOH$ that provides $[OH{]}^{-}$ of $1.5\times {10}^{-3}\text{M}$ will be :
Given: $K_b\left(BOH\right)=1.5\times {10}^{-5}$

1. $1.5\times {10}^{-2}M$
2. $0.015M$
3. $1.5\times {10}^{-4}M$
4. $0.15M$

Q. The percentage dissociation $\left(\alpha \right)$ of $C{H}_{3}COOH$ having dissociation constant $K_a=1.8\times {10}^{-5}M$ is given as $5$%.
Find the inital concentration of $C{H}_{3}COOH$.

1. $2.44\times {10}^{-2}M$
2. $1.98\times {10}^{-2}M$
3. $1.28\times {10}^{-3}M$
4. $6.84\times {10}^{-3}M$

Q. If the degree of dissociation of water at ${70}^{o}C$ is $1.28\times {10}^{-8}$. Then what is the ionic product of water at this temperature?

1. $25\times {10}^{-16}{M}^2$
2. $1.52\times {10}^{-14}{M}^2$
3. $1.28\times {10}^{-8}{M}^2$
4. $5.1\times {10}^{-13}{M}^2$

Q. Consider a weak base, $BOH$. Molar concentration of $BOH$ that provides $[OH{]}^{-}$ of $1.5\times {10}^{-3}\text{M}$ will be :
Given: $K_b\left(BOH\right)=1.5\times {10}^{-5}$

1. $1.5\times {10}^{-2}M$
2. $0.015M$
3. $1.5\times {10}^{-4}M$
4. $0.15M$

Q. Which of the following is incorrect for degree of dissociation $\left(\alpha \right)$ ?

1. The value of $\alpha$ can be any value from 0 to 1
2. $\alpha$ can be a fractional value
3. $\alpha$ has no units
4. None of the above

Q. The % of dissociation of water at ${25}^{\circ }C$ is $1.9\times {10}^{-7}$ and density is $1.0gc{m}^{-3}$ The ionic constant for water is :

1. $1.0\times {10}^{-10}$
2. $1.0\times {10}^{-14}$
3. $1.0\times {10}^{-16}$
4. $1.0\times {10}^{-8}$

Q. In aqueous solution 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 for a saturated 0.04 M solution of the carbonic acid

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

Q. At ${50}^{o}C,$ the self-ionisation constant (ionic product) of $N{H}_3$ is given as,
$K_{N{H}_3}=\left[N{H}_4^{+}\right]\left[N{H}_2^{-}\right]={10}^{-30}{M}^2$.
How many $N{H}_2^{-}$ ions are present per $m{m}^3$ of pure liquid ammonia?

1. $600ions/m{m}^3$
2. $6\times {10}^{5}ions/m{m}^3$
3. $6\times {10}^{4}ions/m{m}^3$
4. $6\times {10}^{3}ions/m{m}^3$

Q. An unknown compound A dissociates at ${500}^{\circ }C$ to give products as follows:
$A\left(g\right)\rightleftharpoons B\left(g\right)+C\left(g\right)+D\left(g\right)$
Vapour density of the equilibrium mixture is 60 when it dissociates to the extent to ${20}^{\%}$. What will be the molecular weight (in grams) of Compound A

Q. Which of the following is the correct statement(s) regarding $K_{a_1}$ for the first dissociation and $K_{a_2}$ for the second dissociation of a polyprotic acid $H_{2}C{O}_3$ ?

1. $K_{a_1}$ has less value than $K_{a_2}$
2. $H_{ion}^{+}$ from $H_{2}C{O}_3$ is more easier to obtain compared to $H_{ion}^{+}$ from $HC{O}_3^{-}$
3. $K_{a_1}$ has more value than $K_{a_2}$
4. $\left[H^{+}\right]$ from $H_{2}C{O}_3$ is is more difficult to obtain as compared to $H_{ion}^{+}$ from $HC{O}_3^{-}$

Q. Which of the following is the correct statement(s) regarding $K_{a_1}$ for the first dissociation and $K_{a_2}$ for the second dissociation of a polyprotic acid $H_{2}C{O}_3$ ?

1. $K_{a_1}$ has less value than $K_{a_2}$
2. $H_{ion}^{+}$ from $H_{2}C{O}_3$ is more easier to obtain compared to $H_{ion}^{+}$ from $HC{O}_3^{-}$
3. $K_{a_1}$ has more value than $K_{a_2}$
4. $\left[H^{+}\right]$ from $H_{2}C{O}_3$ is is more difficult to obtain as compared to $H_{ion}^{+}$ from $HC{O}_3^{-}$

Q. What will be the $H^{+}$ ion concentration of 0.01 M $HCN$ solution at equilibrium, if it is 20% ionised?

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

Q. At ${25}^{\circ }C$ molar conductance of $0.1$ molar aqueous solution of ammonium hydroxide is $9.54oh{m}^{-1}c{m}^{2}mo{l}^{-1}$ and at infinite dilution its molar conductance is $238oh{m}^{-1}c{m}^{2}mo{l}^{-1}.$ The degree of ionization of ammonium hydroxide at the same concentration and temperature is : -
(NEET-UG-2013 )

1. $20.800\%$
2. $40.800\%$
3. $2.080\%$
4. $4.008\%$