Which is a nonrenewable source of energy?
Wind
Hydropower
Natural Gas
Solar Energy

Natural Gas

Explanation:

Let's remember: A non-renewable resource means a source that is used faster than it can be replaced. The sun will always be there for solar energy. Wind will always be there for wind energy. Hydropower isn't always there, but it is a semi-renewable source because it is replenished relatively fast. We are left with natural gas, and it takes millions of years to replace.

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.