As we go from species to kingdom in a taxonomic hierarchy,the number of common characteristics

Which of the following complex ions exhibits optical isomerism? ($en = 1,2$-diaminoethane)

Particles of masses $m, 2m, 3m, \ldots, nm$ grams are placed on the same line at distances $l, 2l, 3l, \ldots, nl$ $cm$ from a fixed point. The distance of the centre of mass of the particles from the fixed point in centimetres is

$A$ stunt man jumps his car over a crater as shown (neglect air resistance).

What are the products formed when chlorine is passed through an aqueous hypo solution?

If $\alpha, \beta, \gamma$ are the roots of the equation $x^3+a x^2+b x+c=0$,then $\alpha^{-1}+\beta^{-1}+\gamma^{-1}$ is equal to