Herbarium is a

In which of the following reactions is hydrogen gas not liberated?

$A$ wind with speed $40\,m/s$ blows parallel to the roof of a house. The area of the roof is $250\,m^2.$ Assuming that the pressure inside the house is atmospheric pressure,the force exerted by the wind on the roof and the direction of the force will be $(\rho_{air} = 1.2\,kg/m^3)$

Copper sulphate dissolves in excess of $KCN$ to give

If $\Delta$ is the area of the triangle formed by the positive $x$-axis and the normal and tangent to the circle $x^2+y^2=4$ at $(1, \sqrt{3})$,then $\Delta$ is equal to

$A$ magnetized wire of magnetic moment $M$ and length $L$ is bent into an arc of a circle subtending an angle of $60^{\circ}$ at the center. The new magnetic moment is: