Answer:
Choice A => 1 Liter O₂(g) & 1 Liter H₂(g) at STP conditions contain 2.7 x 10²² molecules of each gas.
Explanation:
At STP conditions 1 mole of 'any gas' ( = O₂(g) & H₂(g) ) contain 6.023 x 10²³ particles (atoms or molecules) and occupies 22.4 Liters.
=> 1 Liter of 'any gas' at STP = 1 Liter 'any gas'/22.4 Liters 'any gas'/mole 'any gas' = 0.045 mole 'any gas' and contains 0.045 mole 'any gas' x 6.023 x 10²³ particles 'any gas'/mole 'any gas' = 2.7 x 10²² particles 'any gas'.
In this problem, 'any gas' refers to O₂(g) & H₂(g). Therefore 1 L O₂(g) contains the same number of molecules as 1 L H₂(g) at STP conditions.
Answer choices B, C & D are incorrect b/c at STP conditions ...
2 Liters CO(g) = 2(2.7 x 10²²) molecules CO(g) = 5.4 x 10²² molecules CO(g)
3 Liters CO₂(g) = 3(2.7 x 10²²)molecules CO₂(g) = 8.1 x 10²² molecules CO₂(g)
0.5 Liters Ne(g) = 0.5(2.7 x 10²²) atoms Ne(g) = 1.35 x 10²² atoms Ne(g)
