$A$ 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 ........ $N$.

If the difference between the roots of the equations $x^2 + ax + b = 0$ and $x^2 + bx + a = 0$ is the same and $a \neq b$,then:

In which of the following compounds,the transition metal is in oxidation state of zero?

When a point source of monochromatic light is placed at a distance of $0.2 \ m$ from a photoelectric cell,the cut-off voltage and saturation current are $0.6 \ V$ and $18 \ mA$ respectively. If the same source is placed at a distance of $0.6 \ m$ from the photoelectric cell,then:

What is formed when oxalic acid is dehydrated with concentrated $H_2SO_4$?

If the slope of one line is twice the slope of the other in the pair of straight lines $ax^2 + 2hxy + by^2 = 0$,then $8h^2$ is equal to (in $ab$)