Physical Chemistry PYQ — Page 47

These are physical properties of an element (A) Sublimation enthalpy (B) Ionisation enthalpy (C) Hydration enthalpy (D) Electron gain enthalpy The total number of above properties that affect the reduction potential is (Integer answer)

The ionization enthalpy of ${\mathrm{Na}}^{+}$ formation from ${\mathrm{Na}}_{(g)}$ is $495.8\mathrm{kJ}{\mathrm{mol}}^{-1},$ while the electron gain enthalpy of $\mathrm{Br}$ is $-325.0\mathrm{kJ}{\mathrm{mol}}^{-1}$. Given the lattice enthalpy of $\mathrm{NaBr}$ is $-728.4\mathrm{kJ}{\mathrm{mol}}^{-1}$ . The energy for the formation of $\mathrm{NaBr}$ ionic solid is $(-)_____{10}^{-1}\mathrm{kJ}{\mathrm{mol}}^{-1}$

Complete combustion of $750g$ of an organic compound provides $420g$ of ${\mathrm{CO}}_{2}$ and $210g$ of ${H}_{2}O$. The percentage composition of carbon and hydrogen in organic compound is $15.3$ and ______ respectively. (Round off to the Nearest Integer)

Isotope(s) of hydrogen which emits low energy ${\beta }^{-}$ particles with ${t}_{1/2}$ value $>12$ years is/are

Assume a cell with the following reaction ${\mathrm{Cu}}_{(s)}+2{\mathrm{Ag}}^{+}(1\times {10}^{-3}M)\rightarrow {\mathrm{Cu}}^{2+}(0.250M)+2{\mathrm{Ag}}_{(s)}$ ${E}_{\mathrm{cell}}^{\circ }=2.97V$ ${E}_{\mathrm{cell}}$ for the above reaction is $V.$ (Nearest integer) $[$ Given : $\mathrm{log}2.5=0.3979,T=298K]$

A ball weighing $10g$ is moving with a velocity of $90m{s}^{-1}.$ If the uncertainty in its velocity is $5%$, then the uncertainty in its position is _ $\times {10}^{-33}m.$ (Rounded off to the nearest integer) [Given: $h=6.63\times {10}^{-34}\mathrm{Js}$]

When $5.1g$ of solid ${\mathrm{NH}}_{4}\mathrm{HS}$ is introduced into a two litre evacuated flask at $27^{\circ}C,20%$ of the solid decomposes into gaseous ammonia and hydrogen sulphide. The ${K}_{p}$ for the reaction at $27^{\circ}C$ is $x\times {10}^{-2}$. The value of $x$ is (Integer answer) [Given $1R=0.082L\mathrm{atm}{K}^{-1}{\mathrm{mol}}^{-1}]$

$2\mathrm{NO}(g)+{\mathrm{Cl}}_{2}(g)\rightleftharpoons 2\mathrm{NOCl}(s)$ This reaction was studied at $-10^{\circ}C$ and the following data was obtained $\begin{matrix}\mathrm{run} & [\mathrm{NO}{]}_{0} & {[{\mathrm{Cl}}_{2}]}_{0} & {r}_{0} \\ 1 & 0.10 & 0.10 & 0.18 \\ 2 & 0.10 & 0.20 & 0.35 \\ 3 & 0.20 & 0.20 & 1.40\end{matrix}$ $[\mathrm{NO}{]}_{0}$ and ${[{\mathrm{Cl}}_{2}]}_{0}$ are the initial concentrations and ${r}_{0}$ is the initial reaction rate. The overall order of the reaction is (Round off to the Nearest Integer).

According to Bohr's atomic theory: (A) Kinetic energy of electron is $\propto \frac{{Z}^{2}}{{n}^{2}}.$ (B) The product of velocity (v) of electron and principal quantum number $(n),'vn'\propto {Z}^{2}.$ (C) Frequency of revolution of electron in an orbit is $\propto \frac{{Z}^{3}}{{n}^{3}}.$ (D) Coulombic force of attraction on the electron is $\propto \frac{{Z}^{3}}{{n}^{4}}.$ Choose the most appropriate answer from the options given below:

$4g$ equimolar mixture of $\mathrm{NaOH}$ and ${\mathrm{Na}}_{2}{\mathrm{CO}}_{3}$ contains $\mathrm{xg}$ of $\mathrm{NaOH}$ and $\mathrm{yg}$ of ${\mathrm{Na}}_{2}{\mathrm{CO}}_{3}.$ The value of $x$ is $g.$ (Nearest integer)

The following data was obtained for chemical reaction given below at $975K$. $2{\mathrm{NO}}_{(g)}+2{H}_{2(g)}\rightarrow {N}_{2(g)}+2{H}_{2}{O}_{(g)}$ $\begin{matrix} & [\mathrm{NO}] & [{H}_{2}] & \mathrm{Rate} \\ & \text{ mol }{L}^{-1} & \text{ mol }{L}^{-1} & {\mathrm{molL}}^{-1}{s}^{-1} \\ (A) & 8\times {10}^{-5} & 8\times {10}^{-5} & 7\times {10}^{-9} \\ (B) & 24\times {10}^{-5} & 8\times {10}^{-5} & 2.1\times {10}^{-8} \\ (C) & 24\times {10}^{-5} & 32\times {10}^{-5} & 8.4\times {10}^{-8}\end{matrix}$ The order of the reaction with respect to $\mathrm{NO}$_____ is [Integer answer]

For a chemical reaction $A\rightarrow B$, it was found that concentration of $B$ is increased by $0.2\mathrm{mol}{L}^{-1}$ in 30 min. The average rate of the reaction is ________ $\times {10}^{-1}\mathrm{mol}{L}^{-1}{h}^{-1}$. (in nearest integer)

In basic medium ${\mathrm{CrO}}_{4}^{2-}$ oxidises ${S}_{2}{O}_{3}^{2-}$ to form ${{\mathrm{SO}}_{4}}^{2-}$ and itself changes into $\mathrm{Cr}{(\mathrm{OH})}_{4}^{-}$.The volume of $0.154{\mathrm{MCrO}}_{4}^{2-}$ required to react with $40\mathrm{mL}$ of $0.25{\mathrm{MS}}_{2}{{O}_{3}}^{2-}$ is _____ $\mathrm{mL}.$ (Rounded-off to the nearest integer)

The reaction that occurs in a breath analyser, a device used to determine the alcohol level in a person's blood stream is $2{K}_{2}{\mathrm{Cr}}_{2}{O}_{7}+8{H}_{2}{\mathrm{SO}}_{4}+3{C}_{2}{H}_{6}O\rightarrow 2{\mathrm{Cr}}_{2}{({\mathrm{SO}}_{4})}_{3}+3{C}_{2}{H}_{4}{O}_{2}+2{K}_{2}{\mathrm{SO}}_{4}+11{H}_{2}O$ If the rate of appearance of ${\mathrm{Cr}}_{2}{({\mathrm{SO}}_{4})}_{3}$ is $2.67\mathrm{mol}{\mathrm{min}}^{-1}$ at a particular time, the rate of disappearance of ${C}_{2}{H}_{6}O$ at the same time is mol ${\mathrm{min}}^{-1}.$ (Nearest integer)

The ${\mathrm{NaNO}}_{3}$ weighed out to make $50\mathrm{mL}$ of an aqueous solution containing $70.0\mathrm{mg}{\mathrm{Na}}^{+}$ per $\mathrm{mL}$ is_ $g$. (Rounded off to the nearest integer) [Given : Atomic weight in ${\mathrm{gmol}}^{-1}-\mathrm{Na}:23;N:14;O:16$]

$224\mathrm{mL}$ of ${\mathrm{SO}}_{2(g)}$ at $298K$ and $1\mathrm{atm}$ is passed through $100\mathrm{mL}$ of $0.1M\mathrm{NaOH}$ solution. The non-volatile solute produced is dissolved in $36g$ of water. The lowering of vapour pressure of solution (assuming the solution is dilute) ($P{^{\circ}}_{({H}_{2}O)}=24\mathrm{mm}$ of $\mathrm{Hg}$) is $x\times {10}^{-2}\mathrm{mm}$ of $\mathrm{Hg}$ the value of $x$ is (Integer answer)

The kinetic energy of an electron in the second Bohr orbit of a hydrogen atom is equal to $\frac{{h}^{2}}{x{\mathrm{ma}}_{0}^{2}}.$ The value of $10x$ is (${a}_{0}$ is radius of Bohr's orbit) (Nearest integer) [Given: $\pi =3.14$]

In order to prepare a buffer solution of $\mathrm{pH}5.74$, sodium acetate is added to acetic acid. If the concentration of acetic acid in the buffer is $1.0M,$ the concentration of sodium acetate in the buffer is ______$M.$ (Round off to the Nearest Integer). $[\mathrm{Given}:\mathrm{pKa}(\text{acetic acid})=4.74]$

The density of $\mathrm{NaOH}$ solution is $1.2g{\mathrm{cm}}^{-3}.$ The molality of this solution is $m$ (Round off to the Nearest Integer): [Use : Atomic masses : $\mathrm{Na}:23.0uO:16.0u$ $H:1.0u$ Density of ${H}_{2}O:1.0g{\mathrm{cm}}^{-3}]$

Identify the process in which change in the oxidation state is five :

For the following graphs,   Choose from the options given below, the correct one regarding order of reaction is :

Potassium chlorate is prepared by electrolysis of $\mathrm{KCl}$ in basic solution as shown by following equation. $6{\mathrm{OH}}^{-}+{\mathrm{Cl}}^{-}\rightarrow {\mathrm{ClO}}_{3}^{-}+3{H}_{2}O+6{e}^{-}$ A current of $\mathrm{xA}$ has to be passed for $10h$ to produce $10.0g$ of potassium chlorate. the value of $x$ is __________. (Nearest integer) (Molar mass of ${\mathrm{KClO}}_{3}=122.6g{\mathrm{mol}}^{-1}F=96500C$)

Which of the following compound CANNOT act as a Lewis base?

For the cell $\mathrm{Cu}(s)|{\mathrm{Cu}}^{2+}(\mathrm{aq})(0.1M)\|{\mathrm{Ag}}^{+}(\mathrm{aq})(0.01M)|\mathrm{Ag}(s)$ the cell potential ${E}_{1}=0.3095V$. For the cell $\mathrm{Cu}(s)|{\mathrm{Cu}}^{2+}(\mathrm{aq})(0.01M)\|{\mathrm{Ag}}^{+}(\mathrm{aq})(0.001M)|\mathrm{Ag}(s)$ the cell potential $=x\times {10}^{-2}V.$ Find value of x (Round off the Nearest Integer). [ Use $:\frac{2.303\mathrm{RT}}{F}=0.059J$ ]