NEET 2021 Chemistry Questions

Which of the following statements is not correct about diborane?

\ce{BF3} is planar and an electron-deficient compound. The hybridization and number of electrons around the central atom, respectively, are:

Match List-I with List-II. List-I: (a) \ce{PCl5}, (b) \ce{SF6}, (c) \ce{BrF5}, (d) \ce{BF3} List-II: (i) Square pyramidal, (ii) Trigonal planar, (iii) Octahedral, (iv) Trigonal bipyramidal

The correct sequence of bond enthalpy of the C-X bond is:

Statement I: Acid strength increases in the order \ce{HF} < \ce{HCl} < \ce{HBr} < \ce{HI}. Statement II: As the size of the elements \ce{F}, \ce{Cl}, \ce{Br}, \ce{I} increases down the group, the bond strength of \ce{HF}, \ce{HBr} and \ce{HI} decreases and so the acid strength increases. In the light of the above statements, choose the correct answer from the options given below:

Which of the following molecules is non-polar in nature?

The compound which shows metamerism is:

An organic compound contains 78% (by wt.) carbon and the remaining percentage of hydrogen. The empirical formula of this compound is: [Atomic wt. of C = 12, H = 1]

Choose the correct skeletal structure for 2,6-dimethyldec-4-ene.

What is the IUPAC name of the organic compound formed in the following reaction? \ce{CH3-CO-CH3 ->[(i) C2H5MgBr, dry ether][(ii) H2O/H+] Product}

The dihedral angle of the least stable conformer of ethane is:

Which of the following is the correct structure of 2,6-dimethyldec-4-ene?

The dihedral angle of the least stable conformer of ethane is:

The major product of the following reaction is: \ce{(CH3)2CH-CH=CH2 ->[HBr][(C6H5CO)2O2] ?}

Identify the missing reagent/chemical in the reaction: \ce{CH3CH2COONa ->[NaOH,\ ?][\Delta] CH3CH3 + Na2CO3}

A particular station of All India Radio, New Delhi, broadcasts on a frequency of $1368$ kHz (kilohertz). The wavelength of the electromagnetic radiation emitted by the transmitter is: [Speed of light, $c = 3 \times 10^{8}$ m s$^{-1}$]

Tritium, a radioactive isotope of hydrogen, emits which of the following particles?

From the following pairs of ions, which one is NOT an iso-electronic pair?

For a reaction $\ce{A -> B}$, the enthalpy of reaction is $-4.2\ kJ\,mol^{-1}$ and the enthalpy of activation is $9.6\ kJ\,mol^{-1}$. The correct potential energy profile for the reaction is shown in which option?

For the irreversible expansion of an ideal gas under isothermal conditions, the correct option is:

\ce{Zr} ($Z=40$) and \ce{Hf} ($Z=72$) have similar atomic and ionic radii because of:

From the following pairs of ions, which one is NOT an isoelectronic pair?

Which of the following reactions is a metal displacement reaction? Choose the right option.

An organic compound contains 78\% (by wt.) carbon and the remaining percentage of hydrogen. The empirical formula of the compound is [at. wt.: C = 12, H = 1]

What is the IUPAC name of the organic compound formed in the following reaction? \ce{CH3COCH3 ->[{(i) C2H5MgBr, dry ether}][{(ii) H2O, H+}] Product}

The intermediate compound \ce{X} in the following reaction is: \ce{C6H5-CH3 ->[CrO2Cl2][CS2] X ->[H3O+] C6H5-CHO}

Match List-I with List-II and choose the correct answer. List-I: (a) \ce{C6H6 ->[{CO, HCl}][{Anhy. AlCl3, CuCl}] C6H5-CHO} (b) \ce{R-CO-CH3 ->[NaOX] R-COO^- + CHX3} (c) \ce{R-CH2-OH + R'COOH ->[{Conc. H2SO4}] } (d) \ce{R-CH2-COOH ->[{(i) X2/Red P}][{(ii) H2O}] } List-II: (i) Hell-Volhard-Zelinsky reaction (ii) Gattermann-Koch reaction (iii) Haloform reaction (iv) Esterification

The product formed in the following reaction is: \ce{4-methyl-2-(2-methoxy-2-oxoethyl)cyclohexan-1-one ->[{NaBH4}][{C2H5OH}] ?} (A cyclohexanone ring bearing a \ce{-CH2COOCH3} methyl-ester side chain and a \ce{CH3} substituent.)

Consider the reaction: \ce{CH3CH2COONa ->[NaOH + ?][\Delta] CH3CH3 + Na2CO3} Identify the missing reagent.

Which of the following statements is not correct?

Deficiency of red blood cells (pernicious anaemia) is the deficiency disease of

The following solutions were prepared by dissolving 10 g glucose (\ce{C6H12O6}) in 250 mL of water (P1), 10 g of urea (\ce{CH4N2O}) in 250 mL of water (P2) and 10 g of sucrose (\ce{C12H22O11}) in 250 mL of water (P3). The right option for the decreasing order of osmotic pressure of these solutions is:

The correct option for the value of vapour pressure of a solution at 45 °C with benzene to octane in molar ratio 3 : 2 is: [At 45 °C vapour pressure of benzene is 280 mm Hg and that of octane is 420 mm Hg. Assume ideal solution]

The major product of the following reaction is: \ce{(CH3)2CH-CH=CH2 + HBr ->[(C6H5CO)2O2] ?}

The major product formed in the dehydrohalogenation of 2-bromopentane is pent-2-ene. This product formation is based on:

The compound which shows metamerism is

What is the IUPAC name of the organic compound formed in the following chemical reaction? \ce{CH3COCH3 ->[\text{(i) } C2H5MgBr,\ \text{dry ether}][\text{(ii) } H2O,\ H+] Product}

Zr (Z = 40) and Hf (Z = 72) have similar atomic and ionic radii because of:

The incorrect statement among the following is:

The molar conductances of \ce{NaCl}, \ce{HCl} and \ce{CH3COONa} at infinite dilution are $126.45$, $426.16$ and $91.0\ \text{S cm}^2\,\text{mol}^{-1}$ respectively. The molar conductance of \ce{CH3COOH} at infinite dilution is. Choose the right option for your answer.

The molar conductivity of $0.007\ \text{M}$ acetic acid is $20\ \text{S cm}^2\,\text{mol}^{-1}$. What is the dissociation constant of acetic acid? Choose the correct option. $\lambda^\circ(\ce{H+}) = 350\ \text{S cm}^2\,\text{mol}^{-1}$, $\lambda^\circ(\ce{CH3COO-}) = 50\ \text{S cm}^2\,\text{mol}^{-1}$

Ethylenediaminetetraacetate (EDTA) ion is:

Match List - I with List - II. List-I (a) $\ce{[Fe(CN)6]^3-}$ (b) $\ce{[Fe(H2O)6]^3+}$ (c) $\ce{[Fe(CN)6]^4-}$ (d) $\ce{[Fe(H2O)6]^2+}$ List-II (i) $5.92$ BM (ii) $0$ BM (iii) $4.90$ BM (iv) $1.73$ BM Choose the correct answer from the options given below.

The slope of the Arrhenius plot ($\ln k$ vs $1/T$) of a first-order reaction is $-5\times 10^{3}$ K. The value of $E_a$ of the reaction is (Given $R = 8.314\ \text{J K}^{-1}\text{mol}^{-1}$):

Identify the compound that will react with Hinsberg's reagent to give a solid which dissolves in alkali.