The first one is the answer
isotopes of an atom have different number of neutrons . the number of protons are not different in isotopes of an atom
Answer : The correct option is, (C) 2, 4 and 5.
Explanation :
Combustion reaction : It is a type of reaction in which a hydrocarbon react with an oxygen molecule to give carbon dioxide, water as a product.
For example : Methane react with oxygen to give carbon dioxide and water.

In the given list of chemical substances,
are in oxide form. They can not be both reactant and product of a single combustion reaction.
In the given list,
is the only hydrocarbon which shows a combustion reaction. That means
react with
to give
and
as a product.
The balanced combustion reaction of
is,

Therefore, the correct answer is, (C) 2, 4, and 5.
It must be made of matter because anything and everything is made up of atoms. The other three options are made of atoms but they are also matter.
The given formula contains two carbon along with six hydrogen and an oxygen.
The possible isomers from
are ethanol and dimethyl ether.
Ehtanol is an alcohol containing a hydroxyl group whereas dimethyl ether is an ether containing an oxygen between two methyl
The structure of two isomers are:
Answer:
It was built to house the employees of the Chernobyl Nuclear Power Plants located 4 kilometers away and became the ninth nuclear city in the Soviet Union.
Explanation: