$A$ point is moving on $y=4-2x^2$. The $x$-coordinate of the point is decreasing at the rate of $5 \text{ units/s}$. Then,the rate at which the $y$-coordinate of the point is changing when the point is at $(1,2)$ is

Five elements $A, B, C, D$ and $E$ have work functions $1.2 \ eV, 2.4 \ eV, 3.6 \ eV, 4.8 \ eV$ and $6 \ eV$ respectively. If light of wavelength $4000 \ \mathring{A}$ is allowed to fall on these elements,then photoelectrons are emitted by:

$A$ particle is projected from a point at an angle $\theta$ with the horizontal direction. At any time $t$,if $p$ is the linear momentum,$y$ is the vertical displacement,and $x$ is the horizontal displacement,which of the following graphs does $NOT$ represent the variation of kinetic energy $(KE)$ of the particle?

Let $A(3-i)$ and $B(2+i)$ be two points in the Argand plane. If the point $P$ represents the complex number $z=x+iy$,which satisfies $|z-3+i|=|z-2-i|$,then the locus of the point $P$ is

The radiation emitted by a star $A$ is $10000$ times that of the sun. If the surface temperatures of the sun and the star $A$ are $6000 \ K$ and $2000 \ K$ respectively,the ratio of the radii of the star $A$ and the sun is : (in $: 1$)

The reaction of $CH_3-CH=CH-C_6H_4-OH$ with $HBr$ gives: