Question

At STP, 1.0 liter of helium contains the same total number of atoms as

Answer 1

Answer: (1) 1.0 L of Ne

Explanation: According to Avogadro's law, 1 mole of every gas occupy 22.4 Liters at STP and contains avogadro's number $6.023\times 10^{23}$ of particles.

Avogadro's Law: This law states that volume is directly proportional to the number of moles of the gas at constant pressure and temperature.

$V\propto n$   (At constant temperature and pressure)

Thus equal volumes contain equal number of atoms.

Hence, 1.0 liter of helium contains the same total number of atoms as

1.0 L of Ne at STP.

Answer 2

The answer is (1) 1.0 L of Ne. The gases under same condition with same volume have the same molar number. And the question is asking the number of atoms. Because the elements given all have same number of atoms when having same molar number.