NOTE: Angles not necessarily drawn to scale.

Step-by-step explanation:

First question mark

The reactants have 1 carbon atom, 4 hydrogen atoms, 4 oxygen atoms

Second question mark

The law of conservation of mass states that during a reactions atoms are conserved over time.

Third Question mark

1 carbon atom , 4 oxygen atoms, 4 hydrogen atoms, or in short number of atoms in the reactants equals number of atoms in the products.