Differentiate between electrovalency and covalency.

What do you understand by the ground state and excited state of the atom?

An insect moves along a circular path of radius $10 \mathrm{cm}$with a constant speed. It takes $1 \min$  to move from a point on the path to the diametrically opposite point, find (i) the distance covered, (ii) the speed, (iii) the displacement and (iv) the average velocity.

In the following distance-time graph, how much B is ahead of A when the motion starts?

What is the speed of B ?

 When and where will A catch B ?

What is the difference between speeds of A and B?

Is the speed of both the trains uniform or non-uniform? Justify your answer.