NEET (UG) 2025 Chemistry Previous Year Questions

Consider the following compounds: $K{O}_2$, $H_2{O}_2$ and $H_{2}S{O}_4$. The oxidation states of the underlined elements in them are, respectively:

For the reaction $\mathrm{A}(\mathrm{g})\rightleftharpoons 2\mathrm{B}(\mathrm{g})$, the backward reaction rate constant is higher than the forward reaction rate constant by a factor of 2500 at $1000\mathrm{K}$. $K_p$ for the reaction at $1000\mathrm{K}$ is [Given: $R=0.0831\mathrm{L}\mathrm{atm}\mathrm{mo}{\mathrm{l}}^{-1}{\mathrm{K}}^{-1}$]

If the rate constant of a reaction is $0.03{\mathrm{s}}^{-1}$, how much time does it take for $7.2\mathrm{mol}{\mathrm{L}}^{-1}$ concentration of the reactant to get reduced to $0.9\mathrm{mol}{\mathrm{L}}^{-1}$?
(Given: $\log 2=0.301$)

Identify the suitable reagent for the following conversion

The ratio of the wavelengths of the light absorbed by a Hydrogen atom when it undergoes $n=2\to n=3$ and $n=4\to n=6$ transitions, respectively, is

Energy and radius of first Bohr orbit of $\mathrm{H}{\mathrm{e}}^{+}$ and $\mathrm{L}{\mathrm{i}}^{2+}$ are given. [$R_H=2.18\times 10^{-18}\mathrm{J}$, $a_0=52.9\mathrm{pm}$]. Choose the correct set:

Among the following, choose the ones with equal number of atoms.
A. $212\mathrm{g}$ of $\mathrm{N}{\mathrm{a}}_2\mathrm{C}{\mathrm{O}}_3(\mathrm{s})$ [molar mass $=106\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$]
B. $248\mathrm{g}$ of $\mathrm{N}{\mathrm{a}}_2\mathrm{O}(\mathrm{s})$ [molar mass $=62\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$]
C. $240\mathrm{g}$ of $\mathrm{NaOH}(\mathrm{s})$ [molar mass $=40\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$]
D. $12\mathrm{g}$ of ${\mathrm{H}}_2(\mathrm{g})$ [molar mass $=2\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$]
E. $220\mathrm{g}$ of $\mathrm{C}{\mathrm{O}}_2(\mathrm{g})$ [molar mass $=44\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$]
Choose the correct answer from the options given below:
(1) A, B, and D only
(2) B, C, and D only
(3) B, D, and E only
(4) A, B, and C only

The correct order of decreasing acidity of the following aliphatic acids is:

Dalton's Atomic theory could not explain which of the following?
(1) Law of constant proportion
(2) Law of multiple proportion
(3) Law of gaseous volume
(4) Law of conservation of mass

Match List I with List II.
List I (Name of Vitamin):
A. Vitamin ${\mathrm{B}}_{12}$ B. Vitamin D
C. Vitamin ${\mathrm{B}}_2$ D. Vitamin ${\mathrm{B}}_6$ List II (Deficiency disease):
I. Cheilosis
II. Convulsions
III. Rickets
IV. Pernicious anaemia
Choose the correct answer from the options given below:

Match List-I with List-II.

List-I
A. Haber process
B. Wacker oxidation
C. Wilkinson catalyst
D. Ziegler catalyst

List-II
I. Fe catalyst
II. $\mathrm{PdC}{\mathrm{l}}_2$ III. $[(\mathrm{PP}{\mathrm{h}}_3{)}_3\mathrm{RhCl}]$ IV. $\mathrm{TiC}{\mathrm{l}}_4$ with $\mathrm{Al}(\mathrm{C}{\mathrm{H}}_3{)}_3$

Choose the correct answer from the options given below:

Out of the following complex compounds, which of the compound will be having the minimum conductance in solution?

Phosphoric acid ionizes in three steps with their ionization constant values $K_{a1}$, $K_{a2}$ and $K_{a3}$, respectively, while $K$ is the overall ionization constant. Which of the following statements are true?
A. $\log K=\log K_{a1}+\log K_{a2}+\log K_{a3}$ B. ${\mathrm{H}}_3\mathrm{P}{\mathrm{O}}_4$ is a stronger acid than ${\mathrm{H}}_2\mathrm{P}{\mathrm{O}}_4^{-}$ and $\mathrm{HP}{\mathrm{O}}_4^{2-}$.
C. $K_{a1}>K_{a2}>K_{a3}$
D. $K_{a1}=\frac{K_{a3}+K_{a2}}{2}$ Choose the correct answer from the options given below:
(1) A and C only
(2) B, C and D only
(3) A, B and C only
(4) A and B only

Which one of the following reactions does NOT belong to "Lassaigne's test"?

Given below are two statements:
Statement I: Like nitrogen that can form ammonia, arsenic can form arsine.
Statement II: Antimony cannot form antimony pentoxide.
In the light of the above statements, choose the most appropriate answer from the options given below:
(1) Both Statement I and Statement II are incorrect
(2) Statement I is correct but Statement II is incorrect
(3) Statement I is incorrect but Statement II is correct
(4) Both Statement I and Statement II are correct

Given below are two statements:
Statement I: A hypothetical diatomic molecule with bond order zero is quite stable.
Statement II: As bond order increases, the bond length increases.
In the light of the above statements, choose the most appropriate answer from the options given below:

Sugar 'X'
A. is found in honey.
B. is a keto sugar.
C. exists in $\alpha$ and $\beta$ - anomeric forms.
D. is laevorotatory.
'X' is:

The major product of the following reaction is

How many products (including stereoisomers) are expected from monochlorination of the following compound?

Which one of the following compounds can exist as cis-trans isomers?