MCQ
What is the molar solubility of $Mn(OH)_2$ $(K_{sp} = 4.5\times10^{-14})$ in a buffer solution contain equal moles of $NH_4^+$ and $NH_3$ $(K_b = 1.8\times10^{-5})$ ?
  • A
    $3.0\times10^{-4}$
  • $1.38\times10^{-4}$
  • C
    $1.3\times10^{-3}$
  • D
    $7.3\times10^{-4}$

Answer

Correct option: B.
$1.38\times10^{-4}$
b
Basic buffer $\mathrm{pOH}=\mathrm{pkb}+\log \frac{\left[\mathrm{NH}_{4}^{+}\right]}{\left[\mathrm{NH}_{3}\right]}$

$=4.74$

$\left[\mathrm{OH}^{-}\right]=1.80 \times 10^{-5}$

$\mathrm{K}_{\mathrm{sp}}, \mathrm{Mn}(\mathrm{OH})_{2}=\mathrm{S} \times[\mathrm{OH}]^{2}$

$\therefore S=\frac{k_{s p}}{\left[O H^{-}\right]^{2}}=\frac{4.5 \times 10^{-14}}{1.8^{2} \times 10^{-10}}$

$S=1.38 \times 10^{-4}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

Which of the following arrangements of electrons in mostly likely to be stable :
$40\%$ of a mixture of $0.2\,mol$ of $N_2$ and $0.6\,mol$ of $H_2$ reacts to give $NH_3$ according to the equation.

${N_2}(g)\, + \,3{H_2}(g)\,\rightleftharpoons  \,2N{H_3}\,(g)$

at constant temperature and pressure. Then the ratio of the final volume to the initial volume of gases are.

Which has maximum dipole moment ?
Which of the following is correct with respect to $-I$ effect of the substituents ? ($R =$ alkyl)
Functional group present in sulphonic acid is:
Bond order normally gives idea of stability of a molecular species. All the molecules viz. $H_2,\,\, Li_2$ and $B_2$ have the same bond order yet they are not equally stable. Their stability order is
Major product will be
In the $\ce{P^{3-}, S^{2-}}$ and $\ce{Cl}^-$ ions, the increasing order of size is :
$10\ gm$ of a piece of marble $(CaCO_3)$ was put into excess of $dilute HCl$ acid. When the reaction was complete, $1120\ ml$ of $CO_2$ was obtained at $STP$. The percentage of pure $CaCO_3$ in the marble is ............. $\%$
The amount of energy required to break a bond is same as the amount of energy released when the same bond is formed. In gaseous state, the energy required for homolytic cleavage of a bond is called Bond Dissociation Energy ($BDE$) or Bond Strength. BDE is affected by s-character of the bond and the stability of the radicals formed. Shorter bonds are typically stronger bonds. BDEs for some bonds are given below :

$\begin{array}{l} Cl - Cl ( g ) \longrightarrow Cl ^*( g )+ Cl ^*( g ) \Delta H ^{\circ}=58 kcal mol ^{-1} \\ H _3 C - Cl ( g ) \longrightarrow H _3 C ^*( g )+ Cl ^{\circ}( g ) \Delta H ^{\circ}=85 kcal mol ^{-1} \\ H - Cl ( g ) \quad \longrightarrow H ^*( g ) \quad+ Cl ^*( g ) \Delta H ^{\circ}=103 kcal mol ^{-1} \\\end{array}$

($1$) Correct match of the $C - H$ bonds (shown in bold) in Column $J$ with their BDE in Column $K$ is

Column $J$ Molecule

Column $K$ $\operatorname{BDE}( kcal mol -1)$

$(P)$ $H - C H \left( CH _3\right)_2$ ${ (i) } 132$
$(Q)$ $H - CH _2 Ph$ ${ (ii) } 110$
$(R)$ $H - C H = CH _2$ ${ (iii) } 95$
$(S)$ $H - C \equiv CH$ ${ (iv) } 88$

$(A)$ $P - iii, Q - iv, R - ii, S - i$

$(B)$ $P - i, Q - ii, R - iii, S - iv$

$(C)$ $P - iii, Q - ii, R - i, S - iv$

$(D)$ $P - ii, Q - i, R - iv, S - iii$

($2$) For the following reaction

$CH _4( g )+ Cl _2( g ) \xrightarrow{\text { light }} CH _3 Cl ( g )+ HCl ( g )$

the correct statement is

$(A)$ Initiation step is exothermic with $\Delta H ^{\circ}=-58 kcal mol ^{-1}$

$(B)$ Propagation step involving ${ }^{\circ} CH _3$ formation is exothermic with $\Delta H ^{\circ}=-2 kcal mol ^{-1}$.

$(C)$ Propagation step involving $CH _3 Cl$ formation is endothermic with $\Delta H ^{\circ}=+27 kcal mol ^{-1}$.

$(D)$ The reaction is exothermic with $\Delta H ^{\circ}=-25 kcal mol ^{-1}$.