Question

a boy sitting on a chair placed on tbe floor of room write as many action​

Answer 1

Answer:

Let weight of the boy be W. If this force W be taken as action (downward) on the chair. Equal and opposite force W (Upward) is applied on the boy by the chair which is reaction. So this is the first action reaction pair W-W.  Now this weight W plus the weight of the chair W' applies force on the floor through the four legs of chair. Let P=W+W'. The force P is divided into four forces P1, P2, P3 and P4 (according to sitting posture of the boy) which act downwards through the legs of the chair. If these be taken as actions, equal and opposite (upwards) forces by the floor on the legs will be reactions. So other pairs of action reaction are P1-P1, P2-P2, P3-P3 and P4-P4.