check all of the following changes that would decrease the pressure inside a tank of helium gas. allow some…

Answer:

1. Allow some of the helium to leak out into the air.
2. Place the tank outside on a cold winter day.

Explanation:

Step1: Recall ideal - gas law

The ideal - gas law is $PV = nRT$, where $P$ is pressure, $V$ is volume, $n$ is the number of moles, $R$ is the ideal - gas constant, and $T$ is temperature.

Step2: Analyze effect of gas amount

If some helium leaks out, $n$ decreases. Since $V$ and $T$ are assumed constant in this case (initially), from $P=\frac{nRT}{V}$, a decrease in $n$ leads to a decrease in $P$.

Step3: Analyze effect of temperature

Placing the tank on a cold winter day decreases $T$. With $V$ and $n$ constant, from $P=\frac{nRT}{V}$, a decrease in $T$ leads to a decrease in $P$.

Step4: Analyze hot summer day case

Placing the tank in the trunk of a car on a hot summer day increases $T$. With $V$ and $n$ constant, from $P=\frac{nRT}{V}$, an increase in $T$ leads to an increase in $P$.

Step5: Analyze adding more gas case

Adding more helium atoms increases $n$. With $V$ and $T$ constant, from $P=\frac{nRT}{V}$, an increase in $n$ leads to an increase in $P$.