Question

If $A=\{2,3,5\}$, then $A\cup \varphi$ and $\varphi \cup A$.

Answer 1

$\varphi =$ null element

$\therefore$ union of some element $A$ with a null element is element itself

$A\cup \varphi =\varphi \cup A=A$

Ans $\{2,3,5\}$