A litre of buffer solution contains 0.1 mole of each of NH$_3$ and NH$_4$Cl. On the addition of 0.02 mole of HCl by dissolving gaseous HCl, the pH of the solution is found to be _____________ $\times$ 10$^{-3}$ (Nearest integer)

[Given : $\mathrm{pK_b(NH_3)=4.745}$

$\mathrm{\log2=0.301}$

$\mathrm{\log3=0.477}$

$\mathrm{T=298~K]}$

50 mL of 0.1 M CH₃COOH is being titrated against 0.1 M NaOH. When 25 mL of NaOH has been added, the pH of the solution will be _____________ $\times$ 10^$-$2. (Nearest integer)

(Given : pK_a (CH₃COOH) = 4.76)

log 2 = 0.30

log 3 = 0.48

log 5 = 0.69

log 7 = 0.84

log 11 = 1.04

$25.0 \mathrm{~mL}$ of $0.050 ~\mathrm{M} ~\mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}$ is mixed with of of is at . The ratio of and is ___________.

$600 \mathrm{~mL}$ of $0.01~\mathrm{M} ~\mathrm{HCl}$ is mixed with $400 \mathrm{~mL}$ of . The of the mixture is ___________ . (Nearest integer)

The $\mathrm{pH}$ at which $\mathrm{Mg}(\mathrm{OH})_2\left[\mathrm{~K}_{\mathrm{sp}}=1 \times 10^{-11}\right]$ begins to precipitate from a solution containing ions is __________.

The dissociation constant of acetic acid is $x\times10^{-5}$. When 25 mL of 0.2 $\mathrm{M~CH_3COONa}$ solution is mixed with 25 mL of 0.02 solution, the pH of the resultant solution is found to be equal to 5. The value of is ____________

$\mathrm{K}_{\mathrm{a}}$ for butyric acid $\left(\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{COOH}\right)$ is . The of solution of butyric acid is __________ . (Nearest integer)

If the solubility product of PbS is 8 $\times$ 10^$-$28, then the solubility of PbS in pure water at 298 K is x $\times$ 10^$-$16 mol L. The value of x is __________. (Nearest Integer)

20 mL of $0.1 ~\mathrm{M} ~\mathrm{NaOH}$ is added to $50 \mathrm{~mL}$ of $0.1 ~\mathrm{M}$ acetic acid solution. The of the resulting solution is ___________ (Nearest integer)

An analyst wants to convert $1 \mathrm{~L} \mathrm{~HCl}$ of $\mathrm{pH}=1$ to a solution of of . The volume of water needed to do this dilution is __________ . (Nearest integer)

The $\mathrm{pH}$ of an aqueous solution containing $1 \mathrm{M}$ benzoic acid $\left(\mathrm{pK}_{\mathrm{a}}=4.20\right)$ and sodium benzoate is 4.5. The volume of benzoic acid solution in of this buffer solution is _________ . (given : )