JEE Main 2010 — Physical Chemistry

The correct order of $\mathrm{E}_{\mathrm{SR}^2 / \mathrm{M}}^0$ values with negative sign for the four successive elements $\mathrm{Cr}, \mathrm{Mn}, \mathrm{Fe}$ and $\mathrm{Co}$ is

Ionisation energy of $\mathrm{He}^{+}$is $19.6 \times 10^{-18} \mathrm{~J} \mathrm{atom}^{-1}$. The energy of the first stationary state $(\mathrm{n}=1)$ of $\mathrm{Li}^{2+}$ is

On mixing, heptane and octane form an ideal solution. At $373 \mathrm{~K}$, the vapour pressures of the two liquid components (heptane and octane) are $105 \mathrm{kPa}$ and $45 \mathrm{kPa}$ respectively. Vapour pressure of the solution obtained by mixing $25.0 \mathrm{~g}$ of heptane and $35 \mathrm{~g}$ of octane will be (molar mass of heptane $=100 \mathrm{~g} \mathrm{~mol}^{-1}$ an dof octane $=114 \mathrm{~g} \mathrm{~mol}^{-1}$ ).

The standard enthalpy of formation of $\mathrm{NH}_3$ is $-46.0 \mathrm{~kJ} \mathrm{~mol}^{-1}$. If the enthalpy of formation of $\mathrm{H}_2$ from its atoms is $-436 \mathrm{~kJ} \mathrm{~mol}^{-1}$ and that of $\mathrm{N}_2$ is $-712 \mathrm{~kJ} \mathrm{~mol}^{-1}$, the average bond enthalpy of $\mathrm{N}-\mathrm{H}$ bond in $\mathrm{NH}_3$ is

For a particular reversible reaction at temperature $T, \Delta H$ and $\Delta S$ were found to be both $+v e$. If $T_e$ is the temperature at equilibrium, the reaction would be spontaneous when

The Gibbs energy for the decomposition of $\mathrm{Al}_2 \mathrm{O}_3$ at $500^{\circ} \mathrm{C}$ is as follows : $$ \frac{2}{3} \mathrm{Al}_2 \mathrm{O}_3 \rightarrow \frac{4}{3} \mathrm{Al}+\mathrm{O}_2, \Delta_{\mathrm{r}} \mathrm{G}=+966 \mathrm{~kJ} \mathrm{~mol}^{-1} $$ The potential difference needed for electrolytic reduction of $\mathrm{Al}_2 \mathrm{O}_3$ at $500^{\circ} \mathrm{C}$ is at least

The energy required to break one mole of $\mathrm{Cl}-\mathrm{Cl}$ bonds in $\mathrm{Cl}_2$ is $242 \mathrm{~kJ} \mathrm{~mol}^{-1}$. The longest wavelength of light capable of breaking a single $\mathrm{Cl}-\mathrm{Cl}$ bond is $\left(\mathrm{c}=3 \times 10^8 \mathrm{~ms}^{-1}\right.$ and $\left.\mathrm{N}_{\mathrm{A}}=6.02 \times 10^{23} \mathrm{~mol}^{-1}\right)$

If sodium sulphate is considered to be completely dissociated into cations and anions in aqueous solution, the change in freezing point of water $\left(\Delta \mathrm{T}_{\mathrm{f}}\right)$, when $0.01 \mathrm{~mol}$ of sodium sulphate is dissolved in $1 \mathrm{~kg}$ of water, is $\left(\mathrm{K}_{\mathrm{f}}=1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\right)$

In aqueous solution the ionization constants for carbonic acid are $\mathrm{K}_1=4.2 \times 10^{-7}$ and $\mathrm{K}_2=4.8 \times 10^{-11}$ Select the correct statement for a saturated $0.034 \mathrm{M}$ solution of the carbonic acid.

The correct sequence which shows decreasing order of the ionic radii of the elements is

Solubility product of silver bromide is $5.0 \times 10^{-13}$. The quantity of potassium bromide (molar mass precipitation of $\mathrm{AgBr}$ is

The time for half life period of a certain reaction $A \rightarrow$ products is 1 hour. When the initial concentration of the reactant ' $A$ ', is $2.0 \mathrm{~mol} \mathrm{~L}^{-1}$, how much time does it take for its concentration to come from $0.50$ to $0.25 \mathrm{~mol} \mathrm{~L}^{-1}$ if it is a zero order reaction?

At $25^{\circ} \mathrm{C}$, the solubility product of $\mathrm{Mg}(\mathrm{OH})_2$ is $1.0 \times 10^{-11}$. At which $\mathrm{pH}$, will $\mathrm{Mg}^{2+}$ ions start precipitating in the form of $\mathrm{Mg}(\mathrm{OH})_2$ from a solution of $0.001 \mathrm{M} \mathrm{Mg}^{2+}$ ions ?

If $10^{-4} \mathrm{dm}^3$ of water is introduced into a $1.0 \mathrm{dm}^3$ flask to $300 \mathrm{~K}$, how many moles of water are in the vapour phase when equilibrium is established? (Given : Vapour pressure of $\mathrm{H}_2 \mathrm{O}$ at $300 \mathrm{~K}$ is $3170 \mathrm{~Pa} ; \mathrm{R}=8.314 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$ )

Consider the reaction : $$ \mathrm{Cl}_2(\mathrm{aq})+\mathrm{H}_2 \mathrm{~S}(\mathrm{aq}) \rightarrow \mathrm{S}(\mathrm{s})+2 \mathrm{H}^{+}(\mathrm{aq})+2 \mathrm{Cl}^{-}(\mathrm{aq}) $$ The rate equation for this reaction is rate $=\mathrm{k}\left[\mathrm{Cl}_2\right]\left[\mathrm{H}_2 \mathrm{~S}\right]$ Which of these mechanisms is/are consistent with this rate equation? (A) $\mathrm{Cl}_2+\mathrm{H}_2 \rightarrow \mathrm{H}^{+}+\mathrm{Cl}^{-}+\mathrm{Cl}^{+}+\mathrm{HS}^{-} \quad$ (slow) $$ \mathrm{Cl}^{+}+\mathrm{HS}^{-} \rightarrow \mathrm{H}^{+}+\mathrm{Cl}^{-}+\mathrm{S} \text { (fast) } $$ (B) $\mathrm{H}_2 \mathrm{~S} \Leftrightarrow \mathrm{H}^{+}+\mathrm{HS}^{-} \quad$ (fast equilibrium) $\mathrm{Cl}_2+\mathrm{HS}^{-} \rightarrow 2 \mathrm{Cl}^{-}+\mathrm{H}^{+}+\mathrm{S} \quad$ (slow)