An element that is an alkali metal is what?

very reactive

Explanation:

They form salts and alkali (acid-neutralizing) compounds such as baking soda. In pure form, they are very soft metals which catch fire on contact with water. (These metals are not found free in nature). These elements are Lithium(Li), Sodium(Na), Potassium(K), Rubidium(Rb), Cesium(Cs), and Francium(Fr)

answer: populations of walruses and polar bears will decline

explanation:

you put it

this is true, assuming that the allele is completely recessive and incomplete dominance is not a factor.