Question

B. How many oxygen atoms are on the Reactants side h2+02

Answer 1

Those are the reactants, since their is not a arrow pointing to the products.

And there is a subscript '2', which means that O = 2

Answer: 2

Answer 2

2 oxygen atoms because the subscript is the number of atoms of that element (though if there is a coefficient then you multiply the subscript by the coefficient to get the total number of atoms of the element).