NEET 2023 Chemistry Questions

Which of the following statements is not correct about diborane?

The correct order of dipole moments for molecules \ce{NH3}, \ce{H2S}, \ce{CH4} and \ce{HF}, is

Which one of the following statements is incorrect related to Molecular Orbital Theory?

Amongst the following, the total number of species NOT having eight electrons around the central atom in its outermost shell is: \ce{NH3}, \ce{AlCl3}, \ce{BeCl2}, \ce{CCl4}, \ce{PCl5}

The number of $\sigma$ bonds, $\pi$ bonds and lone pairs of electrons in pyridine (\ce{C5H5N}), respectively, are:

The correct order of energies of the molecular orbitals of the \ce{N2} molecule is:

An ideal gas expands isothermally from $10^{-3}\ \text{m}^3$ to $10^{-2}\ \text{m}^3$ at $300\ \text{K}$ against a constant pressure of $10^{5}\ \text{N\,m}^{-2}$. The work done on the gas is:

Reversible expansion of an ideal gas under isothermal and adiabatic conditions is shown in the figure ($\ce{A->B}$ isothermal expansion, $\ce{A->C}$ adiabatic expansion on a $p$–$V$ plot). Which of the following options is NOT correct?

Which amongst the following options is the correct relation between change in enthalpy and change in internal energy?

The equilibrium concentrations of the species in the reaction $\ce{A + B <=> C + D}$ are $2$, $3$, $10$ and $6\ \text{mol\,L}^{-1}$, respectively, at $300\ \text{K}$. $\Delta G^\circ$ for the reaction is (Given $R = 2\ \text{cal\,mol}^{-1}\text{K}^{-1}$).

Consider the following reaction: $\ce{2H2(g) + O2(g) -> 2H2O(g)}$, $\Delta_r H^\circ = -483.64\ \text{kJ}$. What is the enthalpy change for the decomposition of one mole of water?

Which of the following is correctly matched?

The element expected to form the largest ion to achieve the nearest noble gas configuration is:

Which one of the following represents all isoelectronic species?

Assertion (A): Lithium and beryllium, unlike their other respective group members, form compounds with pronounced ionic character. Reason (R): Lithium and magnesium have similar properties due to the diagonal relationship.

The correct sequence given below, containing a neutral, an acidic, a basic and an amphoteric oxide respectively, is:

Which amongst the following compounds will show geometrical isomerism?

Which amongst the following compounds/species is least basic?

Given below are two statements: Statement I: In an organic compound, when inductive and electromeric effects operate in opposite directions, the inductive effect predominates. Statement II: Hyperconjugation is observed in o-xylene. In the light of the above statements, choose the correct answer from the options given below.

In Lassaigne's extract of an organic compound, both nitrogen and sulphur are present, which gives a blood-red colour with \ce{Fe^3+} due to the formation of:

Which amongst the following compounds would be most readily dehydrated under acidic conditions?

The relation between $n_m$ ($n_m$ = the number of permissible values of the magnetic quantum number $m$) for a given value of the azimuthal quantum number $l$ is:

Which one of the following represents all isoelectronic species?

Given below are two statements: Statement I: The value of the wave function $\psi$ depends upon the coordinates of the electron in the atom. Statement II: The probability of finding an electron at a point within an atom is proportional to the orbital wave function $\psi$. In the light of the above statements, choose the correct answer from the options given below.

The incorrect set of quantum numbers from the following is:

On balancing the given redox reaction, the coefficients $a$, $b$ and $c$ are found to be, respectively: \ce{$a$ Cr2O7^2-(aq) + $b$ SO3^2-(aq) + $c$ H^+(aq) -> 2Cr^3+(aq) + $b$ SO4^2-(aq) + $c$/2 H2O(l)}

The $E^\circ$ values are: \ce{Al+/Al} $= +0.55$ V, \ce{Tl+/Tl} $= -0.34$ V, \ce{Al^3+/Al} $= -1.66$ V and \ce{Tl^3+/Tl} $= +1.26$ V. Identify the incorrect statement.

The correct option for a redox couple is

The weight (g) of two moles of the organic compound obtained by heating sodium ethanoate with sodium hydroxide in the presence of calcium oxide is

The mass of \ce{CO2} produced by heating 20 g of 20\% pure limestone is (at. mass Ca = 40) \ce{CaCO3 ->[1200 K] CaO + CO2}

The density of a 1 M solution of a compound X is 1.25 g mL$^{-1}$. The molality of the solution is (molar mass of X = 85 g mol$^{-1}$)

Consider the following compounds/species: (i) naphthalene; (ii) cyclopentadienyl anion; (iii) cyclobutadiene; (iv) cyclopropenyl anion; (v) cyclopropenyl cation; (vi) cyclooctatetraene; (vii) anthracene. The number of compounds/species which obey Hückel's rule is ______.

Which amongst the following compounds will show geometrical isomerism?

Identify the final product [D] in the following sequence: \ce{CH3CHO ->[{(i) LiAlH4}][{(ii) H3O+}] [A] ->[{H2SO4}][\Delta] [B] ->[HBr] [C] ->[{C6H5Br, Na}][{dry ether}] [D]}

Complete the following reaction. Cyclohexanone $[A]$ reacts with \ce{HCN} to give $[B]$, which on treatment with conc. \ce{H2SO4}/heat gives $[C]$. $C$ is:

Identify the product (A) in the following reaction. The substrate is 1-(4-acetylphenyl)ethan-1-one type compound bearing two \ce{-COCH3} (acetyl) groups, treated with \ce{Zn-Hg} / conc. \ce{HCl}: \ce{substrate ->[Zn-Hg][conc. HCl] A + 2 H2O}

Identify the major product obtained when 2-acetylbenzaldehyde (an ortho-disubstituted benzene bearing \ce{-CO-CH3} and \ce{-CHO}) is treated with \ce{2[Ag(NH3)2]+} and \ce{3OH-} on heating.

The major product formed in the following conversion is: A cyclopentanone bearing a \ce{-CH2COCH3} (2-oxopropyl) side chain treated with (i) \ce{NaBH4}, then (ii) \ce{H2SO4}, heat.

Consider the reaction: \ce{CH3COCH3 ->[dil. Ba(OH)2] X} The functional groups present in compound \ce{X} are

Reagents which can be used to convert alcohols to carboxylic acids are: (A) \ce{CrO3 - H2SO4} (B) \ce{K2Cr2O7 + H2SO4} (C) \ce{KMnO4 + KOH}/\ce{H3O+} (D) \ce{Cu}, 573 K (E) \ce{CrO3}, \ce{(CH3CO)2O} Choose the most appropriate answer:

Identify $X$ in the following reactions: \ce{R-COOH ->[{(i) X}][{(ii) H2O/HCl}] R-CH2OH} \ce{R-CH=CH2 ->[{(i) X}][{(ii) H2O, NaOH, H2O2}] R-CH2-CH2-OH}

The following conversion is known as: \ce{C6H5-COCl ->[H2][Pd-BaSO4] C6H5-CHO}

Identify the product in the following reaction: cyclobutyl chloride \ce{->[{(i) KCN}][{(ii) H2O/HCl, \Delta}] ->[{(iii) Br2/red P}][{(iv) H2O}]} Product.

Identify the final product [D] in the following sequence: \ce{CH3CHO ->[(i) LiAlH4][(ii) H3O+] [A] ->[H2SO4,\ \Delta] [B] ->[HBr] [C] ->[C6H5Br,\ Na/\text{dry ether}] [D]}

The compound shown — \ce{C6H5-CH=CH-CH(Br)-CH2-CH3} (a benzene ring with a \ce{-CH=CH-} unit, then an sp$^3$ carbon bearing \ce{Br} adjacent to the \ce{C=C}) — is an example of a:

Identify the final product in the following sequence: \ce{C6H5N2^+ Cl^- ->[CuBr/HBr] (i) ->[Mg/\text{dry ether}] (ii) ->[H2O] Product}

Identify the product (P) in the following reaction: \ce{(CH3)2CH-CH(OH)-CH3 + HBr -> P} (the alcohol is 3-methylbutan-2-ol)

Which of the following reactions of alkyl halides produces an isocyanide (isonitrile) as the major product? (P) \ce{R-X + HCN ->} (Q) \ce{R-X + AgCN ->} (R) \ce{R-X + KCN ->} (S) \ce{R-X + NaCN ->[H2O/C2H5OH]} Choose the most appropriate answer.

The correct order for the rate of $\alpha,\beta$-dehydrohalogenation of the following compounds is: (i) \ce{CH3CH2CH2CH2I} (1-iodobutane, 1$^\circ$) (ii) \ce{CH3CH2CHI-CH3} (2-iodobutane, 2$^\circ$) (iii) \ce{(CH3)3C-I} (2-iodo-2-methylpropane, 3$^\circ$)

Choose the correct sequence of reagents for the conversion of 4-nitrotoluene to 2-bromotoluene.

Identify $X$ in the following reaction. $\ce{p\text{-}Br\text{-}C6H4\text{-}Cl}$ (1.0 mol) $\ce{->[\text{Mg (1.0 mol)}][\text{dry ether}]}$ Intermediate $\ce{->[D2O]}$ $X$

Identify the product in the following reaction. Chlorocyclobutane $\ce{->[\text{(i) KCN}]}$ $\ce{->[\text{(ii) H2O/HCl, }\Delta]}$ $\ce{->[\text{(iii) Br2/red P}]}$ $\ce{->[\text{(iv) H2O}]}$ Product

Consider the following reaction and identify the major product (P): \ce{CH3-CH(CH3)-CH(OH)-CH3 ->[HBr] P} (3-methylbutan-2-ol)

Which amongst the following would be most readily dehydrated under acidic conditions?

Consider the following reaction and identify the products A and B: \ce{C6H5-CH2-O-C6H5 ->[HI][\Delta] A + B} (benzyl phenyl ether)

The major product formed in the following conversion is: Substrate: 2-(2-oxopropyl)cyclopentan-1-one (a cyclopentanone ring bearing a \ce{-CH2-CO-CH3} side chain at C-2). Reagents: (i) \ce{NaBH4}; (ii) \ce{H2SO4}, $\Delta$.

Reagents which can be used to convert alcohols to carboxylic acids are: (A) \ce{CrO3 - H2SO4} (B) \ce{K2Cr2O7 + H2SO4} (C) \ce{KMnO4 + KOH/H3O+} (D) \ce{Cu, 573 K} (E) \ce{CrO3, (CH3CO)2O} Choose the most appropriate answer from the options given below.

Identify 'X' in the following reactions: \ce{R-COOH ->[\text{(i) X}][\text{(ii) } H2O/HCl] R-CH2OH} \ce{R-CH=CH2 ->[\text{(i) X}][\text{(ii) } H2O,\ NaOH,\ H2O2] R-CH2-CH2-OH}

Molar conductance of an electrolyte increases with dilution according to the equation: $\Lambda_m = \Lambda_m^\circ - A\sqrt{c}$. Which of the following statements are true? (A) This equation applies to both strong and weak electrolytes. (B) Value of the constant $A$ depends upon the nature of the solvent. (C) Value of constant $A$ is same for both \ce{BaCl2} and \ce{MgSO4}. (D) Value of constant $A$ is same for both \ce{BaCl2} and \ce{Mg(OH)2}.

The correct value of cell potential (in volt) for the reaction that occurs when the following two half cells are connected is: \ce{Fe^2+(aq) + 2e- -> Fe(s)}, $E^\circ = -0.44\ \text{V}$ \ce{Cr2O7^2- + 14H+ + 6e- -> 2Cr^3+ + 7H2O}, $E^\circ = +1.33\ \text{V}$

The $E^\circ$ values are given as: $E^\circ_{\ce{Al+/Al}} = +0.55\ \text{V}$ and $E^\circ_{\ce{Tl+/Tl}} = -0.34\ \text{V}$; $E^\circ_{\ce{Al^3+/Al}} = -1.66\ \text{V}$ and $E^\circ_{\ce{Tl^3+/Tl}} = +1.26\ \text{V}$. Identify the incorrect statement.

The correct option for a redox couple is

The conductivity of centimolar solution of \ce{KCl} at $25\,^\circ\text{C}$ is $0.0210\ \text{ohm}^{-1}\text{cm}^{-1}$ and the resistance of the cell containing the solution at $25\,^\circ\text{C}$ is $60\ \text{ohm}$. The value of cell constant is

Which one of the following statements is \textbf{not} correct?

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. \textbf{Assertion A:} A reaction can have zero activation energy. \textbf{Reason R:} The minimum extra amount of energy absorbed by reactant molecules so that their energy becomes equal to the threshold value is called activation energy. In the light of the above statements, choose the correct answer from the options given below:

For a certain reaction, the rate $=k[A]^2[B]$. When the initial concentration of $A$ is tripled keeping the concentration of $B$ constant, the initial rate would

The correct option for the rate law that corresponds to an overall first order reaction is

For a reaction \ce{3A -> 2B}, the average rate of appearance of B is given by $\frac{\Delta[\ce{B}]}{\Delta t}$. The correct relation between the average rate of appearance of B and the average rate of disappearance of A is:

Which one of the following statements is not correct?

Which of the following statements is not correct?

Given below are two statements: Statement I: A unit formed by the attachment of a base to the 1' position of sugar is known as a nucleoside. Statement II: When a nucleoside is linked to phosphorous acid at the 5'-position of the sugar moiety, we get a nucleotide. In the light of the above statements, choose the correct answer from the options given below:

Cheilosis occurs due to deficiency of _________.

The stability of \ce{Cu^2+} salts is more than \ce{Cu^+} salts in aqueous solution due to

Which of the following statements are INCORRECT? A. All the transition metals except scandium form MO oxides which are ionic. B. The highest oxidation number corresponding to the group number in transition metal oxides is attained in \ce{Sc2O3} to \ce{Mn2O7}. C. Basic character increases from \ce{V2O3} to \ce{V2O4} to \ce{V2O5}. D. \ce{V2O4} dissolves in acids to give \ce{VO4^3-} salts. E. \ce{CrO} is basic but \ce{Cr2O3} is amphoteric. Choose the correct answer from the options given below:

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Ionisation enthalpy increases along each series of the transition elements from left to right. However, small variations occur. Reason (R): There is a corresponding increase in nuclear charge which accompanies the filling of electrons in the inner d-orbitals. In the light of the above statements, choose the most appropriate answer from the options given below.

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Ionisation enthalpies of early actinoids are lower than for early lanthanoids. Reason (R): Electrons are entering 5f orbitals in actinoids which experience greater shielding from nuclear charge. In the light of the above statements, choose the correct answer from the options given below:

The homoleptic complex from the following complexes is:

Which complex compound is the most stable?

Which of the following forms a set of a complex and a double salt, respectively?

Type of isomerism exhibited by the compounds \ce{[Cr(H2O)6]Cl3}, \ce{[Cr(H2O)5Cl]Cl2.H2O} and \ce{[Cr(H2O)4Cl2]Cl.2H2O}, and the value of the coordination number (CN) of the central metal ion in all these compounds, respectively, is:

The density of a 1 M solution of a compound 'X' is $1.25\ \text{g mL}^{-1}$. The correct option for the molality of the solution is (Molar mass of compound X $= 85\ \text{g}$):

Which amongst the following aqueous solutions of electrolytes will have minimum elevation in boiling point? Choose the correct option.

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Helium is used to dilute oxygen in diving apparatus. Reason (R): Helium has high solubility in \ce{O2}. In the light of the above statements, choose the correct answer from the options given below.

Which of the following reactions will NOT give a primary amine as the product?

Identify the final product in the following reaction sequence: \ce{C6H5N2+Cl- ->[(i) Cu2Br2/HBr][(ii) Mg/dry\ ether][(iii) H2O] Product}

Choose the correct sequence of reagents in the conversion of 4-nitrotoluene to 2-bromotoluene.