What is the half-life of a radioisotope if a 50-g sample becomes 25 g after 18 days?
O A. 25 days
O B. 9 days
O C. 50 days
O D. 18 days

18 DAYS IS THE HALF LIFE OF THE RADIOISOTOPE.

Explanation:

Using the formula

Nt = No * (1/2)^t/t1/2

where;

Nt = amount remaining = 25 g

No = Initial amounrt of the radioisotope = 50 g

t = time elapsed = 18 days

t1/2 = half life = unknown

Substitute the values into the equation and obtain the half life of the radioisotope;

Nt = No * (1/2) ^t/t1/2

25 = 50 * (1/2) ^18/t1/2

25 /50 =  (1/2)^18/ t1/2

1/2 = (1/2)^18/t1/2

1/2)^1 = (1/2)^18/t1/2

1 = 18/t1/2

t1/2 = 18 days.

So therefore the half life of the radioisotope is 18 days.

3 hours because it is a decent distance.

i'm assuming that the correct answer is indeed the first one/ "a"..