Simply look at the periodic table and fill in what you know based on the table
The number of protons = atomic number
The number of electrons, Which is the same as the atomic number for atoms.
The number of valence electrons that is given by the group that the element is in, the top number of each column in the periodic table.
the answer is true the first one
The answer is NO. During combustion of hydrogen, water is produced as an end product. The chemical formulae for combustion of hydrogen are:
2H2 + O2 -->2 H2O
another advantage is that the whole of the fuel load is combusted hence little wastage. This has made the fuel advantageous in its use as rocket fuel since there is no baggage fuel.
Somewhat of the same element, have same amount of protons but different number of neutrons. <span />