Question

A chemical equation is balanced by changing or adding
a.
chemical symbols.
c.
numbers in front of molecules.
b.
subscripts after atoms.
d.
reactants in the product.

Answer 1

numbers in the front of molecules, called coefficients.

for example:

\(O_2 +\color{red}2~H_2\rightarrow \color{red}2~H_2O\)

the 2's are the coefficients needed to balance the reaction (so the amount of each atom is the same on both sides)

Answer 2

You were right thank you !

Answer 3

no problem