The method of concentrating the ore which makes use of the difference in density between ore and impurities is called

Assertion $(A)$: $-NH_2$ group of aniline is ortho,para directing in electrophilic substitutions.
Reason $(R)$: $-NH_2$ group stabilises the arenium ion formed by the ortho,para attack of the electrophile.
The correct answer is

What is the bond angle in $ClO_2$ (OClO) (in $^{\circ}$)?

If the line $2x + 5y = 12$ intersects the ellipse $4x^2 + 5y^2 = 20$ in two distinct points $A$ and $B$,then the mid-point of $AB$ is

The four distinct points $(0,0), (2,0), (0,-2)$ and $(k,-2)$ are concyclic,if $k$ is equal to

The distribution of relative intensity $I(\lambda )$ of blackbody radiation from a solid object versus the wavelength $\lambda $ is shown in the figure. If the Wien displacement law constant is $2.9 \times 10^{-3}\ mK$,what is the approximate temperature of the object in $K$?