The half-life for a 100-gram sample of radioactive element X is 5 days. How much of element X remains after 10 days have passed?

Question

a
25 g
b
12.5 g
c
10o g - no change
d
50 g

Answer 1

To determine how much of element X remains after 10 days, we can use the concept of half-lives.

The half-life of element X is 5 days, so in each half-life, the amount of the radioactive element is reduced by half.

1. After the first half-life (5 days):

   • 100 g / 2 = 50 g remains.

2. After the second half-life (another 5 days, totaling 10 days):

   • 50 g / 2 = 25 g remains.

Therefore, after 10 days, 25 grams of element X will remain.

The correct answer is a) 25 g.

Answer 2

What happens to the volume of a gas when the temperature is decreased?

a
The volume increases.
b
The volume decreases.
c
The mass decreases.
d
The pressure increases.

Answer 3

The relationship between the temperature and volume of a gas is described by Charles' Law, which states that at constant pressure, the volume of a gas is directly proportional to its temperature in Kelvin. This means that if the temperature of a gas decreases, its volume also decreases.

Therefore, the correct answer is:

b) The volume decreases.