What is the half-life of sodium-25 if 1.00 gram of a 16.00-gram sample of sodium-25 remains unchanged after 237 seconds?

(1) 47.4 s (3) 79.0 s

(2) 59.3 s (4) 118 s

Given,

1 gram remain out of 16 grams after 237 seconds.

So,

1g - > 2g - > 4g - > 8g - > 16g

So, 4 half lives have taken palce.

So,

we divide 237 by 4 and we get our answer.

So,

234 / 4 = 59.25 ≈ 59.3

So, the answer is (2) 59.3 seconds