Question

Which would weigh the least:
(1) 2 moles of calcium
(2) 3 gram atoms of nitrogen
(3) 11.2 litres of oxygen gas
(4) 6.023×10^23 molecules of CO2

Answer 1

Answer:

Option (1)

Explanation:

Before finding our answer, we should first calculate the weight of each of the given substances.

For (1):

1 mole of calcium weighs 40 g

=> 2 moles of calcium would weigh 40 * 2 i.e. 80 g [By Unitary Method]

For (2):

1 gram atom of nitrogen weighs 14 g

=> 3 gram atoms of nitrogen would weigh 14 * 3 i.e. 42 g [ By Unitary Method ]

For (3):

22.4 litres of oxygen gas weighs 32 g at STP

=> 11.2 litres of oxygen gas would weigh { (32/22.4) * 11.2 } i.e. 16 g at STP [By Unitary Method]

For (4):

1 mole of Carbon Dioxide gas weighs 44 g

(We know that, Avogadro's number = 6.023 * 10^23)

=> 6.023 * 10^23 molecules of carbon dioxide gas would weigh 44 g.

Now, comparing the values of the above four equations, we get,

2 moles of calcium is the heaviest.

Hence,

The correct answer is option (1).

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