In this task, you are given a question and answer for that. The answer will fill in the blank or will complete the unfinished question. Your task is to provide an explanation based on the given question or fill-in-the-blank statement, and answer.

Question: Dan notices that there were no new trees planted this year. Since there are so few trees in the area, Dan expects the air to be 
 Answer: dry
With fewer trees, the air is drier and droughts are more common.

Question: Katie has a garden and she installs a small waterfall. Since Katie sets the water to flow very slow and gentle over the sloping fall, the erosion at the bottom of the waterfall will be 
 Answer: less
A gentle slope favours slower flow of surface water, reduces erosion, and increases availability of water to plants.

Question: For dating the age of a fossil, and compared to the isotope Francium with a 22 minute half-life, would Carbon 14 with its 5730 year half-life be a 
 Answer: more useful isotope

Because these isotopes decay more slowly, they can be used to date much older specimens.