Well you want the answer with the same letter in it. A.k.a 2. This means they have the same element in them
O2 (Diatomic oxygen that we breathe) and O3 (Ozone that would be deadly to breathe) have different structures.
So the answer is 2
There would be 55.8 g present
You start by diving each quantity given by the atomic wight of each element:
Phosphorus (P) 
Hydrogen (H) 
Then you divide by the lowest number:
for phosphorus
for hydrogen
So the empirical formula will be:

Religion and science are fundamentally incompatible. They disagree profoundly on how we obtain knowledge of the world. Science is based observation and reasoning from observation. Religion assumes that human beings can access a deeper level of information that is not available by either observation or reason.
Answer: Option (a) is the correct answer.
Explanation:
A miscible solution is defined as the one in which two or more than two components are soluble with each other.
So, when hexane is added to heptane then both of them will mix with each other and hence they are miscible. This mixing will lead to formation of more number of ions into the solution as a result, more will be the disorder present in the solution.
As entropy is the degree of randomness present.
Hence, we can conclude that a solution of hexane and heptane will lead to an increase in entropy.