The correct order of ionic radii of $Ce, La, Pm$ and $Yb$ in $+3$ oxidation state is

If $f: R \rightarrow R$ is defined by $f(x) = \frac{1}{2 - \cos 3x}$ for each $x \in R$,then the range of $f$ is

The $d-$orbitals which are involved in the hybridization of the central atom in $ICl_4^{-}$ are:

$A$ wire suspended vertically from one of its ends is stretched by attaching a weight of $200 \ N$ to the lower end. The weight stretches the wire by $1 \ mm$. The elastic energy stored in the wire is ......... $J$.

The masses and radii of the earth and the moon are $M_1, R_1$ and $M_2, R_2$ respectively. Their centres are at a distance $d$ apart. The minimum speed with which a particle of mass $m$ should be projected from a point midway between the two centres so as to escape to infinity is:

Corrosion of iron is essentially an electrochemical phenomenon where the cell reactions are