Question

c) 1 gram of hydrogen ALWAYS reacts with 8 grams of oxygen. Precious mixes 2g of hydrogen with 20g of oxygen. (ii) How much of which of the two reactants remains after the reaction.[2]​

Answer 1

2H2 + O2 ………… 2H2O

4 gm of H2 reacts with 32 gm of O2 and forms 36 gm water .

this means that 1 gm of H2 produces 9 gm of water in excess of oxygen

so 10.2 gm of h2 will produce 9*10.2=91.8 gm of water.