The number of H⁺ ions present in 1 cm³ of a solution whose pH is 10 is:

1.	\(10^{-10}\)	2.	\(10^{-13}\)
3.	\(6.02 \times10^{10}\)	4.	\(6.02 \times10^{13}\)

The \(K_a\) values of formic acid and acetic acid are respectively $1.77\times {10}^{-4}$ and $1.75\times {10}^{-5}$. The ratio of the acid strength of 0.1 N acids is :

1. 0.1

2. 0.3

3. 3.178

4. 100

ZnS is not precipitated by passing H₂S in an acidic medium but CuS is precipitated. The reason for it is

1. ${\mathrm{K}}_{\mathrm{sp}}<mspace\; width="1em"></mspace>\mathrm{CuS}<<{\mathrm{K}}_{\mathrm{sp}}<mspace\; width="1em"></mspace>\mathrm{ZnS}$

2.$<mspace\; width="1em"></mspace>{\mathrm{K}}_{\mathrm{sp}}<mspace\; width="1em"></mspace>\mathrm{CuS}>>{\mathrm{K}}_{\mathrm{sp}}<mspace\; width="1em"></mspace>\mathrm{ZnS}$

3. ${\mathrm{K}}_{\mathrm{sp}}<mspace\; width="1em"></mspace>\mathrm{CuS}={\mathrm{K}}_{\mathrm{sp}}<mspace\; width="1em"></mspace>\mathrm{ZnS}$

4. None of these

Consider the following acids:

The correct order of strength is:
1. II>III>I>IV
2. IV>II>III>I
3. IV>III>II>I
4. III>II>IV>I

The hydrogen ion concentration is 0.2 M ethanoic acid $({\mathrm{K}}_{\mathrm{C}}=2\times {10}^{-5}<mspace\; width="1em"></mspace>\mathrm{mol}<mspace\; width="1em"></mspace>{\mathrm{dm}}^{-3})$ is approximately

1. ${10}^{-4}$

2. $2\times {10}^{-2}$

3. $2\times {10}^{-6}$

4. $2\times {10}^{-3}$

The pH of a solution made by mixing 50 mL of 0.01 M barium hydroxide solution with 50 mL of H₂O is

Find the molar solubility of Fe(OH)₃ in a buffer solution that is 0.10 M in NH₄Cl and 0.10 M in NH₃  :
\(\mathrm{K}_{\mathrm{b}}\left(\mathrm{NH}_3\right)=1.8 \times 10^{-5}\) and 
\(\text K_{ \text {sp}} [ \text {Fe(OH)}_3] = 2.6 \times 10^{-39}\)

A base dissolved in water yields a solution with a hydroxyl ion concentration of \(0.05 \mathrm{~mol}~ \mathrm{litre}^{-1}\). The solution is:

At $25°\mathrm{C}$ the dissociation constant of a base, BOH is $1.0\times {10}^{-12}$, the concentration of hydroxyl ions 0.01 M aqueous solution of the base would become

1. $2.0\times {10}^{-6}<mspace\; width="1em"></mspace>\mathrm{mol}<mspace\; width="1em"></mspace>{\mathrm{L}}^{-1}$

2. $1.0\times {10}^{-5}<mspace\; width="1em"></mspace>\mathrm{mol}<mspace\; width="1em"></mspace>{\mathrm{L}}^{-1}$

3. $1.0\times {10}^{-6}<mspace\; width="1em"></mspace>\mathrm{mol}<mspace\; width="1em"></mspace>{\mathrm{L}}^{-1}$

4. $1.0\times {10}^{-7}<mspace\; width="1em"></mspace>\mathrm{mol}<mspace\; width="1em"></mspace>{\mathrm{L}}^{-1}$