State the rules governing the number of significant figures that result from each of the following operations addition and subtraction; mutiplication and divison

When a comet collides with earth, it adds material to our planet and causes great damage. therefore, a collision like this is a a. destructive force b. constructive force c. geologic process and event d. constructive and destructive force

The climate of the continental united states is generally 1. tropical 2. temperate 3. arctic 4. highland

An atom of which element reacts with an atom of hydrogen to form a bond with the greatest degree of polarity ?