NEET UG Chemistry — Physical Chemistry previous year questions with solutions.
An element, $\mathrm{X}$ has the following isotopic composition: ${ }^{200} \mathrm{X}: 90 \% \quad{ }^{199} \mathrm{X}: 8.0 \quad{ }^{202} \mathrm{X}: 2.0 \%$ The weighted average atomic mass of the naturally-occurring element $\mathrm{X}$ is closest to
In a first order reaction $\mathrm{A} \rightarrow \mathrm{B}$ if $k$ is rate constant and initial concentration of the reactant $\mathrm{A}$ is $0.5 \mathrm{M}$, then the half-life is:
A weak acid, HA and a $\mathrm{K}_a$ of $1.00 \times 10^{-5}$. If $0.100 \mathrm{~mol}$ of this acid is dissolved in one litre of water, the percentage of acid dissociated at equilibrium is closer to:
The efficiency of a fuel cell is given by:
The hydrogen ion concentration of a $10^{-8}$ $\mathrm{M} \mathrm{HCl}$ aqueous solution at $298 \mathrm{~K}\left(\mathrm{~K}_w=\right.$ $\left.10^{-14}\right)$ is:
$1.00 \mathrm{~g}$ of non-eletrolyte solute (molar mass $250 \mathrm{~g} \mathrm{~mol}^{-1}$ ) was dissolved in $51.2 \mathrm{~g}$ of benzene. If the freezing point depression constant, $\mathrm{K}_f$ of benzene is 5.12 $\mathrm{K} \mathrm{kg} \mathrm{mol}^{-1}$, the freezing point of benzene will be lowered by:
A hypothetical electrochemical cell is show below $\stackrel{\Theta}{\mathrm{A}}\left|\mathrm{A}^{+}(x \mathrm{M}) \| \mathrm{B}^{+}(y \mathrm{M})\right| \stackrel{\oplus}{\mathrm{B}}$ The emf measured is $+0.20 \mathrm{~V}$. The cell reaction is:
$\mathrm{E}_{\mathrm{Fe} 2+/ \mathrm{Fe}}^{\mathrm{o}}=-0.441 \mathrm{~V}$ and $\mathrm{E}_{\mathrm{Fe}^{3+} \mathrm{Fe}^{2+}}^{\mathrm{O}}=0.771$ $\mathrm{V}$, the standard EMF of the reaction $\mathrm{Fe}$ $+2 \mathrm{Fe}^{3+} \rightarrow 3 \mathrm{Fe}^{2+}$ will be:
For the reaction: $$ \mathrm{CH}_{4(g)}+2 \mathrm{O}_{2(g)} \rightleftharpoons \mathrm{CO}_{2(g)}+2 \mathrm{H}_2 \mathrm{O}(l) $$ $\Delta \mathrm{H}_r=-170.8 \mathrm{~kJ} \mathrm{~mol}^{-1}$. Which of the following statements is not true?
The orientation of an atomic orbital is governed by:
Assume each reaction is carried out in an open container. For which reaction will $\Delta H=\Delta E ?$
A solution of acetone in ethanol:
Identify the correct statement for change of Gibbs energy for a system $\left(\Delta \mathrm{G}_{\text {system }}\right)$ at constant temperature and pressure:
The enthalpy of hydrogenation of cyclohexene is $-119.5 \mathrm{~kJ} \mathrm{~mol}^{-1}$. If resoance energy of benzene is -150 $\mathrm{kJ} \mathrm{mol}^{-1}$, its enthalpy of hydrogenation would be:
A solution containing 10 g per \(\mathrm{dm}^3\) of urea (molecular mass \(=60 \mathrm{~g} \mathrm{~mol}^{-1}\)) is isotonic with a \(5 \%\) solution of a nonvolatile solute. The molecular mass of this nonvolatile solution is:
During osmosis, flow of water through a semipermeable membrane is:
For the reaction, $2 \mathrm{~A}+\mathrm{B} \rightarrow 3 \mathrm{C}+\mathrm{D}$, which of the following does not express the reaction rate?
Consider the reaction: $\mathrm{N}_{2(g)}+3 \mathrm{H}_{2(g)} \rightarrow$ $2 \mathrm{NH}_{3(g)}$ The equality relationship between $\frac{d\left[\mathrm{NH}_3\right]}{d t}$ and $-\frac{d\left[\mathrm{H}_2\right]}{d t}$ is:
Given: The mass of electron is $9.11 \times$ $10^{-31} \mathrm{~kg}$, Planck constant is $6.626 \times$ $10^{-34} \mathrm{Js}$. The uncertainty involved in the measurement of velocity within a distance of $0.1 Å$ is:
Which of the following pairs constitutes a buffer?
The enthalpy and entropy change for the reaction: $$ \mathrm{Br}_{2(\mathrm{l})}+\mathrm{Cl}_{2(g)} \rightarrow 2 \mathrm{BrCl}_{(g)} $$ are $30 \mathrm{~kJ} \mathrm{~mol}^{-1}$ and $105 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$ respectively. The temperature which the reaction will be in equilibrium is:
At $25^{\circ} \mathrm{C}$, the dissociation constant of a base, $\mathrm{BOH}$, is $1.0 \times 10^{-12}$. The concentration of hydroxyl ions in $0.01 \mathrm{M}$ aqueous solution of the base would be:
The mass of carbon anode consumed (giving only carbon dioxide) in the production of $270 \mathrm{~kg}$ of a aluminium metal from bauxite by the Hall process is: (Atomic mass : A1 = 27)
Copper has face centered cubic (fcc) lattice with interatomic spacing equal to $2.54 Å$. The value of lattice constant for this lattice is: