After 62.0 hours , 1.0 g remains unchanged from a sample of 42k . how much 42k was in the original sample?

The half-life of K-42 is 12.360 hours.

62 hours is just about 5 half-lives, so we'd expect about 1/32 of the original amount to remain after that time. (32 = 2^5)

In fact, it's 12.36 / 62 = 5.016 half-lives.

2^5.016 = 32.36

So if you started with 32.36g in the original sample, it would have decayed down to 1g after 5.016 half-lives.

water and alcohols have similar properties because water molecules contain hydroxyl groups that can form hydrogen bonds with other water molecules and with alcohol molecules, and likewise alcohol molecules can form hydrogen bonds with other alcohol molecules as well as with water.

it's c (engineer's do their work with mechanical stuff not on any living being)