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MCQEasyJEE 2025Mole Concept

JEE Chemistry 2025 Question with Solution

0.1 mol0.1 \, \text{mol} of the following given antiviral compound (P) will weigh _____ ×10−1 g\times 10^{-1} \, \text{g}.

Structural formula of antiviral compound P showing an iodinated pyrimidine base attached to a fluorinated sugar ring, with labeled I, F, NH, O and OH groups; given atomic masses are H 1, C 12, N 14, O 16, F 19, I 127.
  • A

    372372

  • B

    450450

  • C

    500500

  • D

    350350

Answer

Correct answer:A

Step-by-step solution

Standard Method

Given: Mass of compound (P) is required for 0.1 mol0.1 \, \text{mol}.

Find: The value of xx in x×10−1 gx \times 10^{-1} \, \text{g}.

From the structure, the molecular formula is C9H10FIN2O5\mathrm{C_9H_{10}FIN_2O_5}.

Using atomic masses:

Molar mass=(9×12)+(10×1)+(1×19)+(1×127)+(2×14)+(5×16)\text{Molar mass} = (9 \times 12) + (10 \times 1) + (1 \times 19) + (1 \times 127) + (2 \times 14) + (5 \times 16) =108+10+19+127+28+80=372 g mol−1= 108 + 10 + 19 + 127 + 28 + 80 = 372 \, \text{g mol}^{-1}

Now,

Mass=Number of moles×Molar mass\text{Mass} = \text{Number of moles} \times \text{Molar mass} =0.1×372=37.2 g= 0.1 \times 372 = 37.2 \, \text{g}

Write this as

37.2 g=x×10−1 g37.2 \, \text{g} = x \times 10^{-1} \, \text{g}

So,

x=37.210−1=372x = \frac{37.2}{10^{-1}} = 372

Therefore, the value to be filled in the blank is 372372 and the correct option is A.

Direct Molar Mass Shortcut

Given: Molar mass of compound (P) is 372 g mol−1372 \, \text{g mol}^{-1}.

Find: The value in x×10−1 gx \times 10^{-1} \, \text{g} for 0.1 mol0.1 \, \text{mol}.

Directly,

Mass=372×0.1=37.2 g\text{Mass} = 372 \times 0.1 = 37.2 \, \text{g}

Since

37.2=372×10−137.2 = 372 \times 10^{-1}

the required value is 372372. This shortcut works because multiplying by 0.10.1 is the same as shifting the decimal one place left.

Common mistakes

  • Counting the atoms incorrectly from the structure gives a wrong molecular formula. First identify each part of the molecule carefully, then total the number of C\mathrm{C}, H\mathrm{H}, N\mathrm{N}, O\mathrm{O}, F\mathrm{F}, and I\mathrm{I} atoms before calculating molar mass.

  • Using the molar mass directly as the required answer is wrong. 372 g mol−1372 \, \text{g mol}^{-1} is the molar mass, but the question asks for the mass of 0.1 mol0.1 \, \text{mol}, so multiply by 0.10.1 first.

  • Stopping at 37.2 g37.2 \, \text{g} is incomplete because the blank is in the form x×10−1 gx \times 10^{-1} \, \text{g}. Convert 37.237.2 into that format and then report x=372x = 372.

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