NEET UG 2007 — Physical Chemistry

The equilibrium constant of the reaction: $\mathrm{Cu}_{(s)}+2 \mathrm{Ag}_{(a q)}^{+} \rightarrow \mathrm{Cu}_{(a q)}^{2+}+2 \mathrm{Ag}_{(s)}$ $\mathrm{E}^{\mathrm{o}}=0.46 \mathrm{~V}$ at $298 \mathrm{~K}$ is:

The following equilibrium constant are given: $\begin{aligned} \mathrm{N}_2+3 \mathrm{H}_2 & \rightleftharpoons 2 \mathrm{NH}_3 ; \mathrm{K}_1 \\ \mathrm{~N}_2+\mathrm{O}_2 & \rightleftharpoons 2 \mathrm{NO} ; \mathrm{K}_2 \\ \mathrm{H}_2+1 / 2 \mathrm{O}_2 & \rightleftharpoons \mathrm{H}_2 \mathrm{O} ; \mathrm{K}_3 \end{aligned}$ The equilibrium constant for the oxidation of $\mathrm{NH}_3$ by oxygen to give $\mathrm{NO}$ is:

Concentrated of aqueous sulphuric acid is $98 \% \mathrm{H}_2 \mathrm{SO}_4$ by mass and has a density of $1.80 \mathrm{~g} \mathrm{~mL}^{-1}$ Volume of acid required to make one litre of $0.1 \mathrm{M} \mathrm{H}_2 \mathrm{SO}_4$ solution is:

Given that bond energies of $\mathrm{H}-\mathrm{H}$ and $\mathrm{Cl}-\mathrm{Cl}$ are $430 \mathrm{~kJ} \mathrm{~mol}^{-1}$ and $240 \mathrm{~kJ}$ $\mathrm{mol}^{-1}$ respectively and $\Delta \mathrm{H}_{\mathrm{f}}$ for $\mathrm{HCl}$ is $-\mathrm{kJ}$ $\mathrm{mol}^{-1}$, bond enthalpy of $\mathrm{HCl}$ is:

Calculate the $\mathrm{pOH}$ of a solution $25^{\circ} \mathrm{C}$ that contains $1 \times 10^{-10} \mathrm{M}$ of hydronium ions i.e. $\mathrm{H}_3 \mathrm{O}^{+}$:

Consider the following reactions: (i) $\mathrm{H}_{(a q)}^{+}+\mathrm{OH}_{(a q)}^{-} \rightarrow \mathrm{H}_2 \mathrm{O}_{(\mathrm{i})}, \Delta \mathrm{H}$ $=-\mathrm{X}_1 \mathrm{~kJ} \mathrm{~mol}^{-1}$ (ii) $\mathrm{H}_{2(a q)}+\frac{1}{2} \mathrm{O}_{2(a q)} \rightarrow \mathrm{H}_2 \mathrm{O}_{(\mathrm{I})} \Delta \mathrm{H}$ $=-\mathrm{X}_2 \mathrm{~kJ} \mathrm{~mol}^{-1}$ (iii) $\mathrm{CO}_{2(\mathrm{~g})}+\mathrm{H}_{2(g)} \rightarrow \mathrm{CO}_{(g)}+\mathrm{H}_2 \mathrm{O}, \Delta \mathrm{H}$ $=-\mathrm{X}_3 \mathrm{~kJ} \mathrm{~mol}^{-1}$ (iv) $\mathrm{C}_2 \mathrm{H}_{2(g)}+\frac{5}{2} \mathrm{O}_{2(g)} \rightarrow 2 \mathrm{CO}_{2(g)}+\mathrm{H}_2 \mathrm{O}_{(i) \text {, }}$ $\Delta \mathrm{H}=+\mathrm{X}_4 \mathrm{~kJ} \mathrm{~mol}^{-1}$ Enthalpy of formation of $\mathrm{H}_2 \mathrm{O}_{(l)}$ is:

A weak acid, HA and a $\mathrm{K}_a$ of $1.00 \times 10^{-5}$. If $0.100 \mathrm{~mol}$ of this acid is dissolved in one litre of water, the percentage of acid dissociated at equilibrium is closer to:

0.5 molal aqueous solution of a weak acid $(\mathrm{HX})$ is $20 \%$ ionised. If $\mathrm{K}_f$ for water is $1.86 \mathrm{Kg} \mathrm{mol}^{-1}$, the lowering in freezing point of the solution is:

A steady current of $1.5 \mathrm{amp}$ flows through a copper voltameter for 10 minutes. If the electrochemical equivalent of copper is 30 $\times 10^{-5} \mathrm{~g}$ coulomb $^{-1}$, the mass of copper deposited on the electrode will be.

The efficiency of a fuel cell is given by:

If $60 \%$, of a first order reaction was completed in 60 minutes, $50 \%$ of the same reaction would be completed in approximately: $$ (\log 4=0.60, \log 5=0.69) $$

The reaction of hydrogen and iodine monochloride is given as: $\mathrm{H}_{2(g)}+2 \mathrm{ICl}_{(g)} \rightarrow 2 \mathrm{HCl}_{(g)}+\mathrm{I}_{2(g)}$ This reaction is of first order with respect to $\mathrm{H}_{2(g)}$ and $\mathrm{lCl}_{(g)+}$ following mechanisms were proposed Mechanism A: $\mathrm{H}_{2(g)}+2 \mathrm{ICl}_{(g)} \rightarrow 2 \mathrm{HCl}_{(g)}+\mathrm{H}_{2(g)}$ Mechanism B: $\begin{aligned} & \mathrm{H}_{2(g)}+\mathrm{ICl}_{(g)} \rightarrow \mathrm{HCl}_{(g)}+\mathrm{HI}_{(g)} \text { :slow } \\ & \mathrm{Hl}_{(g)}+\mathrm{lCl}_{(g)} \rightarrow \mathrm{HCl}_{(g)}+\mathrm{l}_{2(g)} \text {; fast } \end{aligned}$ Which of the above mechanism(s) can be consistent with the given information about the reaction?

In a first order reaction $\mathrm{A} \rightarrow \mathrm{B}$ if $k$ is rate constant and initial concentration of the reactant $\mathrm{A}$ is $0.5 \mathrm{M}$, then the half-life is:

Consider the following sets of quantum numbers: \(\begin{array}{|c|c|c|c|c|} \hline & n & l & m & s \\ \hline \text {(i) } & 3 & 0 & 0 & +1 / 2 \\ \text {(ii) } & 2 & 2 & 1 & +1 / 2 \\ \text {(iii) } & 4 & 2 & -2 & -1 / 2 \\ \text {(iv) } & 1 & 0 & -3 & -1 / 2 \\ \text {(v) } & 3 & 2 & 3 & +1 / 2 \\ \hline \end{array}\) Which of the following sets of quantum number is not possible?

An element, $\mathrm{X}$ has the following isotopic composition: ${ }^{200} \mathrm{X}: 90 \% \quad{ }^{199} \mathrm{X}: 8.0 \quad{ }^{202} \mathrm{X}: 2.0 \%$ The weighted average atomic mass of the naturally-occurring element $\mathrm{X}$ is closest to

The number of moles $\mathrm{KMnO}_4$ that will be needed to react with one mole of sulphite ion in acidic solution is: