Question

Out of boiling point ($I$), entropy ($II$), $pH$ ($III$) and e.m.f. of a cell ($IV$), intensive properties are :
(A) $I$,$II$
(B) $I$,$II$,$III$
(C) $I$,$III$,$IV$
(D) All of the above

Answer 1

The intensive properties are a type of bulk properties. It does not depend on the size or the amount of the substance under consideration.
Intensive properties are unaffected with the nature of the substance. It is a kind of physical property.

Complete step-by-step answer: In the question, we are supposed to find the intensive property between all the provided options. Intensive properties are a type of physical property which does not depend on the size or the mass of the considered substance.
Now, we would consider each of these properties which are mentioned in the question. Boiling point is one of the most commonly known intensive properties, as one mole of the liquid, for instance water and a thousand moles of water would have equal boiling point.
The next is entropy, which as we all know is not an intensive property because with increase in the amount of the substance the value of entropy also increases. And as we know, intensive properties are not supposed to change with the change in the amount of the substance under consideration.
The third property is pH, which is also an intensive property for the same reason. As one litre of a substance would have the same $pH$ as that of ten litres of the same substance.
Next option is e.m.f of the cell, and it is also known to be an intensive property, as the change in the amount of electrolyte would not change the value of e.m.f of a cell.
So, apart from the entropy, all the properties are intensive and so the correct option would be C.

Hence the correct answer is option (C).

Note: Boiling point of a substance, $pH$ of a substance and e.m.f of a cell are all intensive properties because it remains the same with increase in the amount of the substance.
While in case of entropy, with increase in the amount, the value of entropy also increases, so it is not an intensive property, which makes it an extensive property.