If $A$ and $B$ are any two sets,then $A \cup (A \cap B)$ is equal to

$A$ satellite is launched into a circular orbit of radius $R$ around the Earth,while a second satellite is launched into an orbit of radius $1.02 R$. The percentage difference in the time periods of the two satellites is:

Two electrons occupying the same orbital are distinguished by

What is the atomic number of the element with the maximum number of unpaired $4p$ electrons?

Which of the following is the correct order of acidic strength?

If the angle between the circles $x^2+y^2-2x-4y+c=0$ and $x^2+y^2-4x-2y+4=0$ is $60^{\circ}$,then $c$ is equal to