Question

If $A=\varnothing$ ,the number of subset is __________ and the number of proper subsets is __________.

• A. $1$
• B. $0$

Answer 1

Subsets: If each element of set $A$ is an element of set $B$, then set $A$ is said to be the subset of set $B$. The symbol for the subset is $\subseteq$ . It is written as $A\subseteq B$ that is $A$ is a subset of $B$ while set $B$ is called the superset of $A$.

Subset of $\left\{\right\}$ is $\left\{\right\}$ that is empty set has one subset. If $A$ is any set then $ф\subseteq A$.

All the subsets except the set itself are called proper subsets.

In an empty set, only $1$ subset is there that is itself, therefore proper subset is $0$.