Answer: (1)

Why? Many scientists have contributed to the development of what we now know as the ideal gas law. The earliest contributor to it was Robert Boyle in 1622. He stated that at constant temperature, the product of an ideal gas's pressure and volume is always constant. This law was later called Boyle's Law. Charles's Law was the next addition to the ideal gas law by Jacques Charles in 1787. He stated that the volume of an ideal gas is proportional to the absolute temperature when pressure is kept constant. Joseph Louis Gay-Lussac was next in 1809 when he stated that, the pressure exerted on a container's sides by an ideal gas is proportional to the absolute temperature of the gas. Finally Amedeo Avogadro in 1811 stated that an ideal gas at the same temperature, pressure and volume contains the same number of molecules. This implies that the number of particles of a specific volume of gas is independent of the size of the particle.

Based on the stated laws the combined gas laws was formulated and shows the relationship between pressure, temperature, volume and number of molecules, it can be summarized in the following equation.

PV=kNT where:

P=Pressure

V=Volume

k is the Boltzmann constant (1.381x10^-23j.k^-1)

N= number of molecules or atoms

T= temperature

The above equation is a summery of the relationship between pressure, volume, moles and temperature.

Reason for Answer:

To answer this question it is important to have an understanding of the ideal gas law, as this will be the principle used to determine the number of atoms contained in a liter of gas. Helium at STP is a gas, and so are all the other listed possible answers.

Based on this equation PV = kNT, if the pressure, volume and temperature are kept constant, then the number of molecules of gas will be the same regardless of the gas. The equation does not mention the impact of where the gas falls on the periodic table or that the size of the atom will impact on the number of moles.