Answer: I'm sure it is c
Explanation: that's my answer
One half-life: 5 grams
Two half-lives: 2.5 grams
Answer: 0.225 atm
Explanation:
For this problem, we have to use Boyle's Law.
Boyle's Law: P₁V₁=P₂V₂
Since we are asked to find P₂, let's manipulate the equation.
P₂=(P₁V₁)/V₂

With this equation, the liters cancel out and we will be left with atm.
P₂=0.225 atm
According to Charles' Law the volume of an ideal gas is directly proportional to its absolute temperature in Kelvin keeping the pressure constant.
V∝ T, P is constant
where V, T and P are volume, temperature and pressure
= 
where V₁, T₁, V₂ and T₂ are initial volume, initial temperature, final volume and final temperature.