The melting point of $Zn$ is lower as compared to those of the other elements of the $3d$ series because:

Which of the following ions will exhibit colour in aqueous solutions?

If $f(x) = \frac{1}{1+\frac{1}{x}}$ and $g(x) = \frac{1}{1+\frac{1}{f(x)}}$,then $g^{\prime}(2)$ is equal to

When an object of height $12 \ cm$ is placed at a distance from a convex lens, an image of height $18 \ cm$ is formed on a screen. Without changing the positions of the object and the screen, if the lens is moved towards the screen, another clear image is formed on the screen. The height of this image is (in $cm$)

$A$ solution of $Na_2SO_4$ in water is electrolysed using inert electrodes. The products at cathode and anode are respectively:

Half-life of a radioactive substance is $20 \, min$. The difference between the points of time when it is $33 \%$ disintegrated and $67 \%$ disintegrated is approximately .......... $min$.