Which two samples of gas at STP contain the same total number of molecules?
(1) 1 L of CO(g) and 0.5 L of N2(g)
(2) 2 L of CO(g) and 0.5 L of NH3(g)
(3) 1 L of H2(g) and 2 L of Cl2(g)
(4) 2 L of H2(g) and 2 L of Cl2(g)



Answer :

The answer is 2L of H2(g) and 2L of Cl2(g)

Answer;

(4) 2 L of H2(g) and 2 L of Cl2(g)

Explanation;

- At STP (standard temperature and pressure) 2 L of hydrogen gas and 2 L of chlorine gas will contain the same number of molecules.

- 1 mole of a gas occupies a volume of 22.4 liters at STP. Both hydrogen and chlorine are gases, thus equal volumes of the two gases ( 2 liters) will be equivalent to 2/22.4 moles (0.0893 moles)

- 1 mole is equivalent to 6.0 ×10^23 particles . Thus 2 L of each gas would contain 5.357 × 10 ^22 molecules (0.0893 × 6 ×10^23).