Physical Chemistry PYQ — Page 74

$6.02 \times 10^{20}$ molecules of urea are present in $100 \mathrm{ml}$ of its solution. The concentration of urea solution is

The conjugate base of $\mathrm{H}_2 \mathrm{PO}_4^{-}$is

Which one the following sets of ions represents the collection of isoelectronic species?

For the reaction, $\mathrm{CO}(\mathrm{g})+\mathrm{Cl}_2(\mathrm{~g}) \rightleftharpoons \mathrm{COCl}_2(\mathrm{~g})$ the $\frac{\mathrm{K}_{\mathrm{p}}}{\mathrm{K}_{\mathrm{c}}}$ is equal to

An ideal gas expands in volume from $1 \times 10^{-3} \mathrm{~m}^3$ to $1 \times 10^{-2} \mathrm{~m}^3$ at $300 \mathrm{~K}$ against a constant pressure of $1 \times 10^5 \mathrm{Nm}^{-2}$. The work done is

The molar solubility product is $\mathrm{K}_{\mathrm{sp}}$. ' $\mathrm{s}$ ' is given in terms of $\mathrm{K}_{\mathrm{sp}}$ by the relation

What is the equilibrium expression for the reaction $\mathrm{P}_{4(\mathrm{~s})}+5 \mathrm{O}_{2(\mathrm{~g})} \rightleftharpoons \mathrm{P}_4 \mathrm{O}_{10(\mathrm{~s}}$ ?

Among $\mathrm{Al}_2 \mathrm{O}_3, \mathrm{SiO}_2, \mathrm{P}_2 \mathrm{O}_3$ and $\mathrm{SO}_2$ the correct order of acid strength is

Among the properties (a) reducing (b) oxidising (c) complexing, the set of properties shown by $\mathrm{CN}^{-}$ion towards metal species is

The rate equation for the reaction $2 \mathrm{~A}+\mathrm{B} \longrightarrow \mathrm{C}$ is found to be: rate $\mathrm{k}[\mathrm{A}][\mathrm{B}]$. The correct statement in relation to this reaction is that the

The half - life of a radioisotope is four hours. If the initial mass of the isotope was $200 \mathrm{~g}$, the mass remaining after 24 hours undecayed is

The formation of the oxide ion $\mathrm{O}^{2-}(\mathrm{g})$ requires first an exothermic and then an endothermic step as shown below $\mathrm{O}(\mathrm{g})+\mathrm{e}^{-} \mathrm{O}^{-}(\mathrm{g}) \Delta \mathrm{H}^{\circ}=-142 \mathrm{kJmol}^{-1}$ $\mathrm{O}^{-}(\mathrm{g})+\mathrm{e}^{-} \mathrm{O}^{2-}(\mathrm{g}) \Delta \mathrm{H}^{\circ}=844 \mathrm{kJmol}^{-1}$

Which of the following liquid pairs shows a positive deviation from Raoult's law?

The limiting molar conductivities $\Lambda^{\circ}$ for $\mathrm{NaCl}, \mathrm{KBr}$ and $\mathrm{KCl}$ are 126,152 and $150 \mathrm{~S} \mathrm{~cm}^2 \mathrm{~mol}^{-1}$ respectively. The $\Lambda^{\circ}$ for $\mathrm{NaBr}$ is

Excess of $\mathrm{KI}$ reacts with $\mathrm{CuSO}_4$ solution and then $\mathrm{Na}_2 \mathrm{~S}_2 \mathrm{O}_3$ solution is added to it. Which of the statements is incorrect for this reaction?

For the reaction equilibrium $\mathrm{N}_2 \mathrm{O}_4(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NO}_2(\mathrm{~g})$ the concentrations of $\mathrm{N}_2 \mathrm{O}_4$ and $\mathrm{NO}_2$ at equilibrium are $4.8 \times 10^{-2}$ and $1.2 \times 10^{-2} \mathrm{~mol} \mathrm{~L}^{-1}$ respectively. The value of $\mathrm{K}_{\mathrm{c}}$ for the reaction is

The correct relationship between free energy change in a reaction and the corresponding equilibrium constant $\mathrm{K}_{\mathrm{c}}$ is

The de Broglie wavelength of a tennis ball of mass $60 \mathrm{~g}$ moving with a velocity of 10 metres per second is approximately

For the redox reaction $\mathrm{Zn}(\mathrm{s})+\mathrm{Cu}^{2+}(0.1 \mathrm{M}) \rightarrow \mathrm{Zn}^{2+}(1 \mathrm{M})+\mathrm{Cu}(\mathrm{s})$ taking place in a cell, $\mathrm{E}_{\text {cell }}^0$ is $1.10$ volt. $\mathrm{E}^{\circ}$ for the cell will be $\left(2.303 \frac{\mathrm{RT}}{\mathrm{F}}=0.0591\right)$

When during electrolysis of a solution of $\mathrm{AgNO}_3 9650$ coulombs of charge pass through the electroplating bath, the mass of silver deposited on the cathode will be

For the reaction system: $2 \mathrm{NO}(\mathrm{g})+\mathrm{O}_2(\mathrm{~g}) \rightarrow 2 \mathrm{NO}_2(\mathrm{~g})$ volume is suddenly reduce to half its value by increasing the pressure on it. If the reaction is of first order with respect to $\mathrm{O}_2$ and second order with respect to $\mathrm{NO}$, the rate of reaction will

If liquids $\mathrm{A}$ and $\mathrm{B}$ form an ideal solution

The half-life of a radioactive isotope is three hours. If the initial mass of the isotope were $256 \mathrm{~g}$, the mass of it remaining undecayed after 18 hours would be

If at $298 \mathrm{~K}$ the bond energies of $\mathrm{C}-\mathrm{H}, \mathrm{C}-\mathrm{C}, \mathrm{C}=\mathrm{C}$ and $\mathrm{H}-\mathrm{H}$ bonds are respectively $414,347,615$ and $435 \mathrm{~kJ}$ $\mathrm{mol}^{-1}$, the value of enthalpy change for the reaction $\mathrm{H}_2 \mathrm{C}=\mathrm{CH}_2(\mathrm{~g})+\mathrm{H}_2(\mathrm{~g}) \rightarrow \mathrm{H}_3 \mathrm{C}-\mathrm{CH}_3(\mathrm{~g})$ at $298 \mathrm{~K}$ will be