Thermodynamically the most stable form of carbon is

Bell metal is an alloy of which of the following?

Cyclic hydrocarbon molecule $A$ has all the carbon and hydrogen atoms in a single plane. All the carbon-carbon bonds are of the same length,which is less than $1.54 \ \mathring{A}$ but more than $1.34 \ \mathring{A}$. The $C-C$ bond angle will be

The vector for sleeping sickness is

$A$ charge $q$ is placed at the centre of the line joining two equal charges $Q$. The system of the three charges will be in equilibrium if $q$ is equal to:

An electromagnetic wave of intensity $1400 ~W/m^2$ falls on a metal surface of area $1.5 ~m^2$ and is completely absorbed by it. Find the force exerted by the beam.