Which gas contains the same number of molecules as 9g of water? A) 2g of hydrogen
B) 14g of nitrogen
C) 32g of oxygen
D) 44g of carbon dioxide

B) 14g of nitrogen

Explanation:

To calculate number of molecules in 9g of water, we first convert mass to mole by using mole = mass/molar mass i.e.

mole = 9g/18g/mol of water

mole = 0.5mol

Next, we multiply by 6.022 × 10^23 molecules to get 3.011 × 10^23 molecules in 9g of water (H2O).

- For hydrogen gas: Molar Mass = 2g/mol, mass = 2g

mole = 2/2 = 1

No. of molecules = 1 × 6.022 × 10^23 = 6.022 × 10^23 molecules.

- For Nitrogen gas: Molar Mass = 28g/mol, mass = 14g

mole = 14/28 = 0.5mol

No. of molecules = 0.5 × 6.022 × 10^23 = 3.011 × 10^23 molecules.

- For Oxygen gas: Molar Mass = 32g/mol, mass = 32g

mole = 32/32 = 1mol

No. of molecules = 1 × 6.022 × 10^23 = 6.022 × 10^23 molecules.

- For carbondioxide gas: Molar Mass = 44g/mol, mass = 44g

mole = 44/44 = 1mol

No. of molecules = 1 × 6.022 × 10^23 = 6.022 × 10^23 molecules.

Based on he results of each calculation, NITROGEN contains the same number of molecules as 9g of water