Consider the following sequence of reactions: 11.25 mg of chlorobenzene will produce \underline\hspace2cm \times 10^-1 mg of product B. (Consider the reactions result in complete conversion.) [Given molar mass of C, H, O, N and Cl as 12,1,16,14 and 35.5 ~g ~mol^-1 respectively]

Haloalkanes and Haloarenes PYQ — JEE Main 2025 · 28 Jan · Shift 1 · Q22 with Solution

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Correct answer: 93

Identify the reaction sequence

Chlorobenzene on nitration gives nitrochlorobenzene, and subsequent hydrolysis of the chlorine substituent gives nitrophenol as product $B$ .

Thus, overall mole ratio is:

1\text{ mol chlorobenzene} \to 1\text{ mol product }B

Molar mass of chlorobenzene

Chlorobenzene is $\mathrm{C_6H_5Cl}$ .

M(\mathrm{C_6H_5Cl}) = 6(12)+5(1)+35.5 = 72+5+35.5 = 112.5\,\text{g mol}^{-1}

Moles of chlorobenzene taken

Given mass = $11.25\,\text{mg} = 11.25 \times 10^{-3}\,\text{g}$

n = \frac{11.25\times 10^{-3}}{112.5} = 10^{-4}\,\text{mol}

So, moles of product $B$ formed are also:

10^{-4}\,\text{mol}

Molar mass of product $B$

Product $B$ is nitrophenol: $\mathrm{C_6H_5NO_3}$ .

M(\mathrm{C_6H_5NO_3}) = 6(12)+5(1)+14+3(16)

=72+5+14+48=139\,\text{g mol}^{-1}

Mass of product formed

m = nM = 10^{-4}\times 139 = 1.39\times 10^{-2}\,\text{g}

Convert to mg:

1.39\times 10^{-2}\,\text{g} = 13.9\,\text{mg}

Now express as $\underline{\hspace{2cm}} \times 10^{-1}\,\text{mg}$ :

13.9\,\text{mg} = 139\times 10^{-1}\,\text{mg}

So the required integer should be:

\boxed{139}

Comparison with stored answer

Stored correct answer = $93$

My derived answer is $139$ . Hence, I do not agree with the stored answer.

A value of $93$ would correspond to a product of molar mass $93\,\text{g mol}^{-1}$ for $10^{-4}$ mol, which does not match the likely product from the given reaction sequence starting from chlorobenzene under complete conversion to nitrophenol.

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View written solutionFree

Correct answer: 93

Identify the reaction sequence

Chlorobenzene on nitration gives nitrochlorobenzene, and subsequent hydrolysis of the chlorine substituent gives nitrophenol as product $B$ .

Thus, overall mole ratio is:

1\text{ mol chlorobenzene} \to 1\text{ mol product }B

Molar mass of chlorobenzene

Chlorobenzene is $\mathrm{C_6H_5Cl}$ .

M(\mathrm{C_6H_5Cl}) = 6(12)+5(1)+35.5 = 72+5+35.5 = 112.5\,\text{g mol}^{-1}

Moles of chlorobenzene taken

Given mass = $11.25\,\text{mg} = 11.25 \times 10^{-3}\,\text{g}$

n = \frac{11.25\times 10^{-3}}{112.5} = 10^{-4}\,\text{mol}

So, moles of product $B$ formed are also:

10^{-4}\,\text{mol}

Molar mass of product $B$

Product $B$ is nitrophenol: $\mathrm{C_6H_5NO_3}$ .

M(\mathrm{C_6H_5NO_3}) = 6(12)+5(1)+14+3(16)

=72+5+14+48=139\,\text{g mol}^{-1}

Mass of product formed

m = nM = 10^{-4}\times 139 = 1.39\times 10^{-2}\,\text{g}

Convert to mg:

1.39\times 10^{-2}\,\text{g} = 13.9\,\text{mg}

Now express as $\underline{\hspace{2cm}} \times 10^{-1}\,\text{mg}$ :

13.9\,\text{mg} = 139\times 10^{-1}\,\text{mg}

So the required integer should be:

\boxed{139}

Comparison with stored answer

Stored correct answer = $93$

My derived answer is $139$ . Hence, I do not agree with the stored answer.

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