Question

if we write something on black board and leave it uncleaned for a considerable period of time them it becomes day difficult to clean it why?​

Answer 1

Answer:

Because.

Explanation:

If we write something on a black board and leave it uncleaned for a period say 10 - 15 days, we will find that it becomes quite difficult to clean the blackboard afterwards. This is due to the fact that some of the particles of chalk have diffused into surface of the board.

Answer 2

Answer:

we write something on a blackboard and leave it uncleaned for a considerable period of time, we will find that it becomes quite difficult to clean the blackboard afterwards. This is due to the fact that some of the particles of chalk have diffused into the surface of blackboard.