Now balance the chemical reaction by providing the
correct coefficients:
carbon monoxide + hydrogen gas yields
water + methane (CH4)

[?]CO + [?]H2 →[?]H20+ [?]CH4

[ 1 ]CO + [ 3 ]H2 ---> [ 1 ]H20 + [ 1 ]CH4

Explanation:

Let us take a look at the count of each element on the " reactant " side of the equation, first -

Carbon = 1,

Oxygen = 1,

Hydrogen = 2

Respectively do the same for the " products " end -

Hydrogen = 6,

Oxygen = 1,

Carbon = 1

As you can see, Hydrogen is the only element that is not equivalent with respect to the reactant and product sides of the chemical reaction. The " product " end has 3 times that of the number of Hydrogen in the " reactant " end, so the coefficient of Hydrogen on the reactant end should be 3, while the coefficient of Hydrogen on the product end should be 1.

And of course, the rest of the compounds would have a coefficient of 1.

answer carbon and three oxygen atoms;