The solubility product of PbI₂ is $7.47\times {10}^{-9}$ at $15°\mathrm{C}$ and $1.39\times {10}^8$ at $25°\mathrm{C}$. The molar heat of solution of PbI₂ is (use log 1.86=0.2695)

1. 44.29 kJ/mol

2. 46.25 kJ/mol

3. 29.37 kJ/mol

4. 21.15 kJ/mol

Which of the following compounds is in the correct sequence in terms of relative basic strength?

1. ${\mathrm{C}}_2{\mathrm{H}}_5{\mathrm{O}}^{-}>\mathrm{CH}\equiv {\mathrm{C}}^{-}>{\mathrm{OH}}^{-}$

2. $\mathrm{CH}\equiv {\mathrm{C}}^{-}{>}^{-}\mathrm{OH}>{\mathrm{C}}_2{\mathrm{H}}_5{\mathrm{O}}^{-}$

3. $\mathrm{CH}\equiv {\mathrm{C}}^{-}>{\mathrm{C}}_2{\mathrm{H}}_5{\mathrm{O}}^{-}>{\mathrm{OH}}^{-}$

4. ${\mathrm{C}}_2{\mathrm{H}}_5{\mathrm{O}}^{-}>{\mathrm{OH}}^{-}>\mathrm{CH}\equiv {\mathrm{C}}^{-}$

The concentration of CH₃COOH that will have the same [H⁺] as obtained from 10^-2 M HCOOH, is-

$\left(\mathrm{Ka}\right({\mathrm{CH}}_3\mathrm{COOH})={10}^{-5},$ $\mathrm{Ka}\left(\mathrm{HCOOH}\right)={10}^{-4})$

1. 10 M

2. 5 M

3. 10^-1 M

4. 6 M

What happens when NH₄Cl is added to an aqueous solution of NH₄OH?

1. Concentration of $\left[{\mathrm{OH}}^{-}\right]$ ions decreases.

2. Concentration of $\left[{\mathrm{OH}}^{-}\right]$ ions increases.

3. Concentration of $\left[{\mathrm{NH}}_4^{+}\right]$ ions as well as concentration $\left[{\mathrm{OH}}^{-}\right]$ ions increase.

4. Concentration of $\left[{\mathrm{NH}}_4^{+}\right]$ ions decreases.

500 ml of 0.2 M HCl is mixed with 500 ml of 0.2 M CH₃COOH. 25 ml of the mixture is titrated with 0.1 M NaOH solution. By how many units does the pH change from the start to the stage when HCl is just completely neutralized. K_a for acetic acid$=2.0\times {10}^{-5}$.

1. 3.7

2. 4.4

3. 2.0

4. 3.0

When 60 ml of 0.1 M $\mathrm{Ca}{\left({\mathrm{NO}}_3\right)}_2$ is mixed with 40 ml of 0.125 M ${\mathrm{Na}}_2{\mathrm{CO}}_3$, ${\mathrm{CaCO}}_3$ precipitates. If K_sp of ${\mathrm{CaCO}}_3$ is $5\times {10}^{-9}$, then $\left[{\mathrm{CO}}_3^{2-}\right]$ in the resulting solution is

1. $5\times {10}^{-8} \mathrm{M}$

2. $5\times {10}^{-9} \mathrm{M}$

3. $5\times {10}^{-6} \mathrm{M}$

4. $5\times {10}^{-7} \mathrm{M}$

100 ml of 0.3 M NH₄OH is mixed with 100 ml of 0.2 M NaOH. K_b NH₄OH is $1.8\times {10}^{-5}$. The degree of dissociation of NH₄OH is

1. $1.02\times {10}^{-2}$

2. $1.8\times {10}^{-5}$

3. $1.8\times {10}^{-4}$

4. $1.02\times {10}^{-4}$

The ionization constant  of $\left[{\mathrm{NH}}_4^{+}\right]$ in water is $5.6\times {10}^{-10}$ at $25°\mathrm{C}$. The rate constant for the reaction of $\left[{\mathrm{NH}}_4^{+}\right]$ and $\left[{\mathrm{OH}}^{-}\right]$ to form NH₃ and H₂O is $3.4\times {10}^{10} \mathrm{lit} {\mathrm{mol}}^{-1 }{\sec }^{-1}$ at $25°\mathrm{C}$. The rate constant for the proton transfer from water to NH₃ in $\mathrm{lit} {\mathrm{mol}}^{-1} {\sec }^{-1}$ is

1. $6.07\times {10}^5$

2. $6.07\times {10}^{-5}$

3. $6.07\times {10}^{-3}$

4. $6.07\times {10}^{-4}$

The equilibrium constant of ${\mathrm{NH}}_4^{+}$ to NH₃ and H⁺ is 10^-10. The rate constant for ${\mathrm{NH}}_4^{+}+{\mathrm{OH}}^{-}\to {\mathrm{NH}}_3+{\mathrm{H}}_2\mathrm{O}$ is 10¹⁰. The rate constant for ${\mathrm{NH}}_3+{\mathrm{H}}_2\mathrm{O}\to {\mathrm{NH}}_4^{+}+{\mathrm{OH}}^{-}$ is:

1. ${10}^5$

2. ${10}^{20}$

3. ${10}^8$

4. ${10}^9$

An acid base indicator has ${\mathrm{K}}_{\mathrm{a}}=3\times {10}^{-5}$. The acid form of the indicator is red and the basic form is blue. By how much must the pH change in order to change the indicator from 75% red to 75% blue (log 3=0.4770)

1. 0.95

2. 2.3

3. 0.75

4. 5