The Question is from neet-chemistry basic-chemistry-concepts mole-concept, and it was created by the author Mr. S M HUSSAIN

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2.24 L of a gas at STP weighs 3.2 g.  The molecular weight of the gas is:

Mr. S M HUSSAIN · Accepted Answer

## CORE INFORMATION\n✓ **Answer**: B\n## CONCEPT FRAMEWORK\n **Primary Concept**: Ideal Gas Law and Molar Volume\n **Related Topics**: Molecular weight, stoichiometry\n **Prerequisites**: Understanding of STP (Standard Temperature and Pressure), Avogadro's Law\n## SOLUTION PATHWAY\n**Given Information**:\n  Volume (V) = 2.24 L\n  Mass (m) = 3.2 g\n  Conditions: STP (Standard Temperature and Pressure)\n  At STP, 1 mole of any ideal gas occupies 22.4 L.\n**Method & Steps**:\n 1. Determine the number of moles of the gas.\n  Reasoning: We can use the molar volume of a gas at STP to find the number of moles.\n  Formula/Rule:  Number of moles (n) = $\frac{Volume}{Molar\,Volume}$\n 2. Calculate the molecular weight.\n  Working: At STP, the molar volume is 22.4 L/mol.\n  Therefore, n = $\frac{2.24 L}{22.4 L/mol}$ = 0.1 mol\n  Molecular weight (MW) = $\frac{mass}{moles}$ = $\frac{3.2 g}{0.1 mol}$ = 32 g/mol\n  Key Point: Molecular weight is the mass of one mole of a substance.\n 3. State the final answer.\n  Result: The molecular weight of the gas is 32 g/mol.\n  Verification: The calculation is straightforward and uses a well-established relationship between volume, mass, and moles at STP.\n ## OPTION ANALYSIS\nA :x: 16 g/mol: This would be the case if only half the amount of gas (1.12L) was considered.\nB ✓: 32 g/mol: This is the correct molecular weight calculated using the given data and the molar volume at STP.\nC :x: 64 g/mol: This would be double the correct molecular weight.\nD :x: 128 g/mol: This would be four times the correct molecular weight.\n ## LEARNING AIDS\n **Common Mistakes**:\n  1.Incorrect use of molar volume at STP: Using the wrong molar volume (e.g., 2.24 L/mol instead of 22.4 L/mol) will lead to incorrect results.  Remember that at STP, 1 mole of gas occupies 22.4 L.\n  2.Unit errors: Make sure to use consistent units throughout the calculation.  Convert all values to the appropriate units before calculations.\n **Quick Tips**:\n  1.Memorize the molar volume of an ideal gas at STP (22.4 L/mol). This is a crucial value for solving many gas law problems.\n  2.Always check the units to ensure they cancel out properly to give the correct units for the final answer (g/mol in this case).

Mr. S M HUSSAIN · Answer

16 g/mol

Mr. S M HUSSAIN · Answer

The correct Option is "32 g/mol"

Mr. S M HUSSAIN · Answer

64 g/mol

Mr. S M HUSSAIN · Answer

128 g/mol

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