Question

Question 25
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?

a
12.5 g
b
10o g - no change
c
50 g
d
25 g
Question 26
What happens to the volume of a gas when the temperature is decreased?

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

Answer 1

**Question 25:**
To find out how much of the radioactive element X remains after 10 days, we can use the concept of half-lives. The half-life of element X is 5 days.

After 5 days (1 half-life), the amount remaining is:
100 g / 2 = 50 g

After another 5 days (2 half-lives, or a total of 10 days), the amount remaining is:
50 g / 2 = 25 g

So, the correct answer is:
**d) 25 g**

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**Question 26:**
According to Charles's Law, if the temperature of a gas decreases, the volume of the gas also decreases, assuming the pressure remains constant.

Thus, the correct answer is:
**a) The volume decreases.**