the answer is d. this is due to the fact a proton weighs 2000 times more then a electron
The answer to your question would more than likely be chemical energy, natural gas, and chemical energy. but I don't know what grade your in I'm in eighth if your below I know the answer. I'm pretty sure I had a question exactly like this last year but that was last year so if it's wrong sorry. I looked it up on Google to make sure
Group 1 and group 7 of element group consists of alkali metal, which are generally combined with other elements in nature, so they have properties of compound
you add the masses of the reactants, because of conservation of mass. if there are two or more products they will ask you to find the mass of only one product or the sum of the mass of all products
