Which one of the following has maximum genetic diversity in India?

The atomic numbers of elements $A$,$B$,$C$ and $D$ are $Z-1$,$Z$,$Z+1$ and $Z+2$,respectively. If $B$ is a noble gas,choose the correct statements from the following:
$(1)$ $A$ has high electron affinity
$(2)$ $C$ exists in $+2$ oxidation state
$(3)$ $D$ is an alkaline earth metal

If the circle $x^2 + y^2 + 2gx + 2fy + c = 0$ touches the $x$-axis,then:

The same retarding force is applied to stop a train. The train stops after $80 \ m$. If the speed is doubled,then the distance will be

What is the correct order of occurrence ($\%$ by weight) in air of $Ne, Ar$ and $Kr$?

The equation of the circle concentric with the circle $x^2+y^2-6x+12y+15=0$ and having double its area is