Which of the following substances imparts a green color to the burner flame?

$A$ block of mass $1\,kg$ lies on a horizontal surface in a truck. The coefficient of static friction between the block and the surface is $0.6$. If the acceleration of the truck is $5\,m\,s^{-2}$,the frictional force acting on the block is ........ $N$.

The mid-point of a chord of the ellipse $x^2+4y^2-2x+20y=0$ is $(2, -4)$. The equation of the chord is

If the gravitational acceleration at the surface of the Earth is $g$,then the increase in potential energy in lifting an object of mass $m$ to a height equal to half of the radius of the Earth from the surface will be:

Membrane-bound organelles are absent in

If $S_n = 1^3 + 2^3 + \ldots + n^3$ and $T_n = 1 + 2 + \ldots + n$,then