NEET UG Chemistry — Physical Chemistry previous year questions with solutions.
How many gram of cobalt metal will be deposited when a solution of cobalt (II) chloride is electrolyzed with a current of 10 amperes for 109 minutes (1 Faraday = $96,500 \mathrm{C}$; Atomic mass of $\mathrm{Co}=59 u$ )
The value of Planck's constant is $6.63 \times 10^{-34} \mathrm{Js}$. The speed of light is $3 \times 10^{17} \mathrm{nms}^{-1}$. Which value is closest to the wavelength in nanometer of a quantum of light with frequency of $6 \times 10^{15} \mathrm{~s}^{-1} ?$
According to law of photochemical equivalence the energy absorbed (in erg/ mole $)$ is given as $\left(h=6.62 \times 10^{-27}\right.$ ergs, $\mathrm{c}=3 \times 10^{10} \mathrm{~cm} \mathrm{~s}^{-1}, \mathrm{~N}_{\mathrm{A}}=6.02 \times 10^{-23}$ $\left.\mathrm{mol}^{-1}\right)$ :
A button cell used in watches functions as following $\mathrm{Zn}(s)+\mathrm{Ag}_2 \mathrm{O}(s) & +\mathrm{H}_2 \mathrm{O}(l) \rightleftharpoons 2 \mathrm{Ag}(s) + \mathrm{Zn}^{2+}(\alpha q)+2 \mathrm{OH}^{-}(\alpha q)$ If half cell potentials are $\begin{aligned} \mathrm{Zn}^{2+}(a q)+2 e^{-} & \rightarrow \mathrm{Zn}(s) ; E^{\circ}=-0.76 \mathrm{~V} \\ \mathrm{Ag}_2 \mathrm{O}(s)+\mathrm{H}_2 \mathrm{O}(l) & +2 e^{-} \\ & \rightarrow 2 \mathrm{Ag}(s)+2 \mathrm{OH}^{-}(a q), \\ & E^{\circ}=0.34 \mathrm{~V} \end{aligned}$ The cell potential will be
At $100^{\circ} \mathrm{C}$ the $\mathrm{K}_w$ of water is 55 times its value at $25^{\circ} \mathrm{C}$. What will be the $\mathrm{pH}$ of neutral solution? $(\log 55=1.74)$
When 5 litres of a gas mixture of methane and propane is perfectly combusted at $0^{\circ} \mathrm{C}$ and 1 atmosphere, 16 litres of oxygen at the same temperature and pressure is consumed. The amount of heat released from the combustion in kJ $\left(\triangle \mathrm{H}_{\text {eomb }}\left(\mathrm{CH}_4\right)\right.$ $=890 \mathrm{~kJ} \mathrm{~mol}^{-1}, \Delta \mathrm{H}_{\text {comb }}\left(\mathrm{C}_3 \mathrm{H}_8\right)=2220 \mathrm{~kJ}$ $\left.\mathrm{mol}^{-1}\right)$
Which of these is least likely to act as a Lewis base?
At $25^{\circ} \mathrm{C}$ molar conductance of 0.1 molar aqueous solution of ammonium hydroxide is $9.54 \mathrm{ohm}^{-1} \mathrm{~cm}^2 \mathrm{~mol}^{-1}$ and at infinite dilution its molar conductance is $238 \mathrm{ohm}^{-1} \mathrm{~cm}^2 \mathrm{~mol}^{-1}$. The degree of ionisation of ammonium hydroxide at the same concentration and temperature is
Accumulation of lactic acid $\left(\mathrm{HC}_3 \mathrm{H}_5 \mathrm{O}_3\right)$, a monobasic acid in tissues leads to pain and a feeling of fatigue. In a 0.10 $\mathrm{M}$ aqueous solution, lactic acid is $3.7 \%$ dissociates. The value of dissociation constant, $\mathrm{K}_a$, for this acid will be:
The dissociation constant of a weak acid is $1 \times 10^{-4}$. In order to prepare a buffer solution with a pH $=5$, the [Salt]/ [Acid] ratio should be:
Maximum deviation from ideal gas is expected from
The value of $\mathrm{K}_{s p}$ of $\mathrm{CaCO}_3$ and $\mathrm{CaC}_2 \mathrm{O}_4$ are $4.7 \times 10^{-9}$ and $1.3 \times 10^{-9}$ respectively at $25^{\circ} \mathrm{C}$. If the mixture of these two is washed with water, what is the concentration of $\mathrm{Ca}^{2+}$ ions in water?
Equimolar solutions of the following substances were prepared separately. Which one of these will record the highest $\mathrm{pH}$ value?
The correct set of four quantum numbers for the valence electron of rubidium atom $(Z=37)$ is
A mixture of potassium chlorate, oxalic acid and sulphuric acid is heated. During the reaction which element undergoes maximum change in the oxidation number?
In which of the following compounds, nitrogen exhibits highest oxidation state?
In a reaction, $A+B \rightarrow$ Product, rate is doubled when the concentration of $B$ is doubled, and rate increases by a factor of 8 when the concentrations of both the reactants $(A$ and $B$ ) are doubled. Rate law for the reaction can be written as
Standard enthalpy of vaporisation $\Delta_{\mathrm{vap}} H^{\mathrm{s}}$ for water at $100^{\circ} \mathrm{C}$ is $40.66 \mathrm{~kJ} \mathrm{~mol}^{-1}$. The internal energy of vaporisation of water at $100^{\circ} \mathrm{C}$ (in $\left.\mathrm{kJ} \mathrm{mol}^{-1}\right)$ is (Assume water vapour to behave like an ideal gas).
In which of the following reactions, standard reaction entropy changes $\left(\Delta S^{\circ}\right)$ is positive and standard Gibb's energy change $\left(\Delta G^{\circ}\right)$ decreases sharply with increasing temperature?
$p_A$ and $p_B$ are the vapour pressure of pure liquid components, $A$ and $B$, respectively of an ideal binary solution. If $x_A$ represents the mole fraction of component $A$, the total pressure of the solution will be
Identify the wrong statement in the following.
The enthalpy of fusion of water is $1.435 \mathrm{kcal} / \mathrm{mol}$. The molar entropy change for the melting of ice at $0^{\circ} \mathrm{C}$ is
Which of the following compounds can be used as antifreeze in automobile radiators?
Four successive members of the first series of the transition metals are listed below. For which one of them the standard potential $\left(E_{M^{2+} / M}^{\circ}\right)$ value has a positive sign?