Which term best describes the role of hydrogen gas in the formation of a water molecule?
a. catalyst
b. inhibitor
c. product
d. reactan

The answer is D. reactant

The chemical reaction is:

We write the initial substances on the left and they are called reactants. Hydrogen is written on the left, isn't it? ;-)

If you find some mistakes in my English, please let me know!

Nonmetals usually react by gaining electrons

The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .