Chitin is an example of which of the following?

According to the kinetic theory of gases,when two molecules of a gas collide with each other,then:

$A$ straight wire of length $20 \ cm$ carrying a current of $\frac{3}{\pi^2} \ A$ is bent in the form of a circle. The magnetic field at the centre of the circle is

Explain the structures of diborane and boric acid.

Four rods of the same material and having the same cross-section and length have been joined as shown in the figure. The temperature of the junction of the four rods will be . . . . . . $^oC$.

$X$-rays are used in: