Answer:
A calculator has an endifiite shape because all of its atoms are touching each other
Yes hydrogen is a non metal
A combustion reaction of an will generally produce CO2 and H20 -- carbon dioxide and water and/or an oxide
looking at the combustion material C2H2, you know that the end products will be CO2 and H20, so the question is how much of each will you get
well, look at the total amount of carbon atoms, 2 C2, which means a total of 4 carbon atoms in this reaction, since only CO2 has carbon atoms, that means there must be 4 CO2 as an end product and 4 CO2 will use up 4 of 5 O2 molecule leaving only 1 O2 molecule for the H2 reaction.
now O2 has a total of 2 oxygen molecules whereas H20 has only a single oxygen molecule, hence the end product must have 2 H20
check that the H atoms balance out on both sides
