Physical Chemistry PYQ — Page 40

Complete combustion of $1.80g$ of an oxygen containing compound $({C}_{x}{H}_{y}{O}_{z})$ gave $2.64g$ of ${\mathrm{CO}}_{2}$ and $1.08g$ of ${H}_{2}O.$ The percentage of oxygen in the organic compound is :

In a solvent $50%$ of an acid HA dimerizes and the rest dissociates. The van't Hoff factor of the acid is _____$\times {10}^{-2}$ (Round off to the nearest integer)

The solubility product of ${\mathrm{PbI}}_{2}$ is $8.0\times {10}^{-9}.$ The solubility of lead iodide in $0.1$ molar solution of lead nitrate is $x\times {10}^{-6}\mathrm{mol}/L.$ The value of $x$ is _________ (Rounded off to the nearest integer)[Given $\sqrt{2}=1.41$]

A reaction has a half life of $1\mathrm{min}$. The time required for $99.9%$ completion of the reaction is ___ min. (Round off to the Nearest integer) [Use : $\mathrm{ln}2=0.69,\mathrm{ln}10=2.3$]

The conductivity of a weak acid$\mathrm{HA}$ of concentration $0.001\mathrm{mol}{L}^{-1}$ is $2.0\times {10}^{-5}S{\mathrm{cm}}^{-1}$. If ${\Lambda }_{m}^{0}(\mathrm{HA})=190S{\mathrm{cm}}^{2}{\mathrm{mol}}^{-1},$ the ionization constant $({K}_{a})$ of HA is equal to $____$ $\times {10}^{-6}$ (Round off to the Nearest Integer)

The oxygen dissolved in water exerts a partial pressure of $20\mathrm{kPa}$ in the vapour above water. The molar solubility of oxygen in water is ______ $\times {10}^{-5}\mathrm{mol}{\mathrm{dm}}^{-3}.$ (Round off to the Nearest Integer). [Given : Henry's law constant $={K}_{H}=8.0\times {10}^{4}\mathrm{kPa}$ for ${O}_{2}.$ Density of water with dissolved oxygen$=1.0\mathrm{kg}{\mathrm{dm}}^{-3}$]

The number of photons emitted by a monochromatic (single frequency) infrared range finder of power $1\mathrm{mW}$ and wavelength of $1000\mathrm{nm}$, in $0.1$ second is $x\times {10}^{13}$. The value of $x$ is (Nearest integer) $(h=6.63\times {10}^{-34}\mathrm{Js},c=3.00\times {10}^{8}{\mathrm{ms}}^{-1})$:

A $5.0m\mathrm{mol}{\mathrm{dm}}^{-3}$ aqueous solution of $\mathrm{KCl}$ has a conductance of $0.55\mathrm{mS}$ when measured in a cell constant $1.3{\mathrm{cm}}^{-1}$. The molar conductivity of this solution is _______ ${\mathrm{mSm}}^{2}{\mathrm{mol}}^{-1}$. (Round off to the Nearest Integer)

The first order rate constant for the decomposition of ${\mathrm{CaCO}}_{3}$ at $700K$ is $6.36\times {10}^{-3}{s}^{-1}$ and activation energy is $209\mathrm{kJ}{\mathrm{mol}}^{-1}$. Its rate constant (in ${s}^{-1})$ at $600K$ is $x\times {10}^{-6}$. The value of $x$ is (Nearest integer) [Given $R=8.31J{K}^{-1}{\mathrm{mol}}^{-1};\mathrm{log}6.36\times {10}^{-3}=-2.19,{10}^{-4.79}=1.62\times {10}^{-5}]$

Assuming that $\mathrm{Ba}(\mathrm{OH}{)}_{2}$ is completely ionised in aqueous solution under the given conditions the concentration of ${H}_{3}{O}^{+}$ ions in $0.005M$ aqueous solution of $\mathrm{Ba}(\mathrm{OH}{)}_{2}$ at $298K$ is _________ $\times {10}^{-12}\mathrm{mol}{L}^{-1}.$ (Nearest integer)

$83g$ of ethylene glycol dissolved in $625g$ of water. The freezing point of the solution is ..... K. (Nearest integer) [Use : Molal Freezing point depression constant of water $=1.86K\mathrm{kg}{\mathrm{mol}}^{-1}$ Freezing point of water $=273K$ Atomic masses : $C:12.0u,O:16.0u,H:1.0u]$

$\mathrm{Emf}$ of the following cell at $298K$ in $V$ is $x\times {10}^{-2}$ $\mathrm{Zn}|{\mathrm{Zn}}^{2+}(0.1M)\|{\mathrm{Ag}}^{+}(0.01M)|\mathrm{Ag}$ The value of $x$ is ________________ (Rounded off to the nearest integer) $[\mathrm{Given}:{E}_{{\mathrm{Zn}}^{2+}/\mathrm{Zn}}^{\theta }=-0.76V;{E}_{{\mathrm{Ag}}^{+}/\mathrm{Ag}}^{\theta }=+0.80V;\frac{2.303\mathrm{RT}}{F}=0.059]$

Sucrose hydrolyses in acid solution into glucose and fructose following first order rate law with a half-life of $3.33h$ at $25^{\circ}C.$ After $9h,$ the fraction of sucrose remaining is $f.$ The value of ${\mathrm{log}}_{10}(\frac{1}{f})$ is ________ $\times {10}^{-2}.$ (Rounded off to the nearest integer) [Assume: In$10=2.303,\mathrm{ln}2=0.693$]

For the first order reaction $A\rightarrow 2B,1$ mole of reactant A gives $0.2$ moles of $B$ after $100$ minutes. The half life of the reaction is ...... min. (Round off to the nearest integer). [Use $:\mathrm{ln}2=0.69,\mathrm{ln}10=2.3$ Properties of logarithms $:\mathrm{ln}{x}^{y}=y\mathrm{ln}x$ $\mathrm{ln}(\frac{x}{y})=\mathrm{ln}x-\mathrm{ln}y]$ (Round off to the nearest integer)

The oxidation states of nitrogen in $\mathrm{NO},{\mathrm{NO}}_{2},{N}_{2}O$ and ${\mathrm{NO}}_{3}^{-}$ are in the order of :

Given below are two statements: Statement I : In the titration between strong acid and weak base methyl orange is suitable as an indicator. Statement II : For titration of acetic acid with $\mathrm{NaOH}$ phenolphthalein is not a suitable indicator. In the light of the above statements, choose the most appropriate answer from the options given below:

At $298.2K$ the relationship between enthalpy of bond dissociation (in $\mathrm{kJ}{\mathrm{mol}}^{-1}$) for hydrogen $({E}_{H})$ and its isotope, deuterium $({E}_{D})$, is best described by:

Match List - I with List - II : <table class="pyq-table"><tbody><tr><td></td><td>List - I (Parameter)</td><td></td><td>List - II (Unit)</td></tr><tr><td>(a)</td><td>Cell constant</td><td>(i)</td><td>$S{\mathrm{cm}}^{2}{\mathrm{mol}}^{-1}$</td></tr><tr><td>(b)</td><td>Molar conductivity</td><td>(ii)</td><td>Dimensionless</td></tr><tr><td>(c)</td><td>Conductivity</td><td>(iii)</td><td>${m}^{-1}$</td></tr><tr><td>(d)</td><td>Degree of dissociation of electrolyte</td><td>(iv)</td><td>${\Omega }^{-1}{m}^{-1}$</td></tr></tbody></table>

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 $(-)_____{10}^{-1}\mathrm{kJ}{\mathrm{mol}}^{-1}$

Consider the complete combustion of butane, the amount of butane utilized to produce $72.0g$ of water is ______ $\times {10}^{-1}g$. (in nearest integer)

The $\mathrm{pH}$ of ammonium phosphate solution, if ${\mathrm{pk}}_{a}$ of phosphoric acid and ${\mathrm{pk}}_{b}$ of ammonium hydroxide are $5.23$ and $4.75$ respectively, is

Consider titration of $\mathrm{NaOH}$ solution versus $1.25M$ oxalic acid solution. At the end point following burette readings were obtained. (i) $4.5\mathrm{mL}$ (ii) $4.5\mathrm{mL}$ (iii) $4.4\mathrm{mL}$ (iv) $4.4\mathrm{mL}$ (v) $4.4\mathrm{mL}$ If the volume of oxalic acid taken was $10.0\mathrm{mL}$ then the molarity of the $\mathrm{NaOH}$ solution is ___$M$. (Rounded-off to the nearest integer)

The resistance of conductivity cell with cell constant $1.14{\mathrm{cm}}^{-1}$, containing $0.001M\mathrm{KCl}$ at $298K$ is $1500\Omega$. The molar conductivity of $0.001M\mathrm{KCl}$ solution at $298K$ in $S{\mathrm{cm}}^{2}{\mathrm{mol}}^{-1}$ is (Integer answer)

The orbital having two radial as well as two angular nodes is: