Chemistry Q51 – JEE-MAIN 2026

Home Chemistry Basic ChemistryQuestion #39

Number of moles and number of molecules in

1.4187

L of

S O_{2}

at STP respectively are

Clue 1 of 3: Molar Volume Concept

Recall that at Standard Temperature and Pressure (STP), one mole of any ideal gas occupies a specific volume.

🧠 Full Solution Path

Step 1: Calculate the number of moles✦ Active

At STP, the molar volume of any ideal gas is $22.4$ L/mol. The given volume of $S O_{2}$ is $1.4187$ L. The number of moles ( $n$ ) can be calculated as:

n = \frac{Volume}{Molar Volume at STP} = \frac{1.4187 L}{22.4 L/mol}

Step 2: Determine the number of moles (numerical value)○ Expand

Performing the division, we get:

n \approx 0.0633348 mol

Rounding to four decimal places, the number of moles is approximately

0.0633

mol.

💡 Teacher's Secret Hint

Ensure to use the correct molar volume for STP (22.4 L/mol).

Step 3: Calculate the number of molecules○ Expand

The number of molecules ( $N$ ) is obtained by multiplying the number of moles by Avogadro's number ( $N_{A} = 6.022 \times 10^{23}$ molecules/mol):

N = n \times N_{A} = 0.0633348 mol \times 6.022 \times 10^{23} molecules/mol

N \approx 0.3813 \times 10^{23} molecules

N \approx 3.813 \times 10^{22} molecules

Comparing this with the given options,

3.812 \times 10^{22}

is the closest value.

💡 Teacher's Secret Hint

Pay attention to significant figures and scientific notation in the final answer.

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Chemistry Question 51 – JEE-MAIN 2026

Clue 1 of 3: Molar Volume Concept

🧠 Full Solution Path