Alkali metals are extremely reactive because they a. have very small atomic masses. b. are not solids at room temperature.
c. have one valance electron that is easily removed to form a positive ion.

Amethod of procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses.

Is there any opitions? if you have the periodic table, the noble gases are 8a family, the halogen are the 7a family, and the nonmetal are  carbon, nitrogen, phosphorus, oxygen, sulfur, selenium, fluorine, chlorine, bromine, iodine and astatine.

It is increased due to the doppler effect. (apex)