Answer:

Explanation:
1. First take the cylinder volume formula:

2. Then take the values for the radius and the height of the cylinder and replace them into the formula:

3. Solve the equation:



Answer:
the number of neutrons in the nucleus
Explanation:
The mass number 205 is the total number of protons and neutrons in the nucleus. Lead has 82 protons, so a mass number of 205 indicates a nucleus with 123 neutrons.
Similarly, the mass number 208 indicates a lead nucleus with 126 neutrons.
The difference in atomic structure is the difference in the number of neutrons in the nucleus.
At STP
1L O₂ → 2L CO₂
xL O₂ → 5.0L CO₂
x=2.5 L