Question

1. relative to one liter of nitrogen at satp, one liter of carbon dioxide at the same temperature and pressure would have

molecules with a greater average kinetic energy
the same mass
50% more gas molecules
the same number of moles.

Explanation:

Step1: Recall Avogadro's law

At the same temperature and pressure, equal volumes of gases contain the same number of moles. Since we have one - liter of nitrogen and one - liter of carbon dioxide at SATP (same temperature and pressure), the number of moles of nitrogen ($n_{N_2}$) and carbon dioxide ($n_{CO_2}$) are equal according to $n=\frac{V}{V_m}$, where $V$ is the volume of the gas and $V_m$ is the molar volume (constant at a given temperature and pressure).

Step2: Analyze average kinetic energy

The average kinetic energy of gas molecules depends only on the temperature. Since the temperature is the same for both gases at SATP, they have the same average kinetic energy. So the first option is incorrect.

Step3: Analyze mass

The molar mass of $N_2$ is $M_{N_2}=2\times14\ g/mol = 28\ g/mol$, and the molar mass of $CO_2$ is $M_{CO_2}=12 + 2\times16\ g/mol=44\ g/mol$. Since $n_{N_2}=n_{CO_2}$ and $m = nM$, and $M_{CO_2}>M_{N_2}$, the mass of $CO_2$ is greater than that of $N_2$. So the second option is incorrect.

Step4: Analyze number of gas molecules

Since $n_{N_2}=n_{CO_2}$, and the number of molecules $N = nN_A$ (where $N_A$ is Avogadro's number), the number of molecules of $N_2$ and $CO_2$ are the same. So the third option is incorrect.

Answer:

The same number of moles.