Answer :
The weight of one mole of gas is 39.9 g.
Option (A) is correct.
Given:
Density of the gas at STP = 1.78 g L⁻¹
Molar volume of any gas at STP = 22.4 L
We know that weight = mass = density × volume.
1. Calculate the weight of 1 liter of gas:
Weight of 1 liter of gas = Density of the gas = 1.78 g
2. Calculate the weight of 22.4 liters of gas (which is one mole of gas at STP):
Weight of 22.4 liters of gas = Weight of 1 liter of gas × 22.4
= 1.78 g/L × 22.4 L
= 39.872 g
Rounded to one decimal place, this is approximately 39.9 g.
So, the weight of one mole of gas is approximately 39.9 grams.
Option (A) is correct.
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Question
The density of a gas is 1.78 g L−1 at STP. The weight of one mole of gas is:
A. 39.9 g
B. 3.56 g
C. 29 g
D. 22.4 g
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