Your body makes NAD and FAD from two B vitamins, niacin and riboflavin. The recommended dietary allowance
for niacin is 20 mg daily and for riboflavin, 1.7 mg. These
amounts are thousands of times less than the amount of
glucose your body needs each day to fuel its energy needs.
Why is the daily requirement for these vitamins so small?

hydrogen is a compound or a single element and a element is a pure substence that cannot be separated into simpler subtances

clorine is a compound its a chemical substance that forms when two or more different elements combine

so both hydrogen and clorine are compounds

in a chemical reaction, the atoms and molecules produced by the reaction are called products. no new atoms are created, and no atoms are destroyed. in a chemical reaction, reactants contact each other, bonds between atoms in the reactants are broken, and atoms rearrange and form new bonds to make the products.