Problem: David was working in his chemistry lab. He selected two isotopes, sample A and sample B. Sample A had longer half-life, but sample B had shorter half-life. After some time he checked sample A when its one half-life had passed. He noted it as sample A1. Then he came back to see it again when two half-lives had passed. He noted it as sample A2. Would sample A1 have less or more isotopes than sample A2?

A: more

Problem: Mark works as a scientist for a molecular research institute. Today, he has three samples of molecule in front of him, sample A, sample B, and sample C. Sample A is a straight-chain molecule; sample B is a branched-chain molecule; and sample C is a cyclic molecule. Mark's job is to determine the characteristics of each sample. In which sample the chain of carbon atoms would not form a ring, sample B or sample C?

A: sample B

Problem: Dan is a geneticist and studied two villages from 2,000 years ago. Village A displayed traces of a large population that grew larger over the years, while village B had a small and declining population and was more isolated geographically. Which village didn't have a reduced gene pool?

A: Village A

Problem: Two ladies sit in a coffee shop. Patty smokes three packs of cigarettes a day, but her good friend Julie, doesn't smoke. They are both 65 years old. They are enjoying a coffee. Which lady has a lower risk of getting mouth cancer?

A:
Julie