Question

Which of the following is not an endothermic reaction:
(a) Thermal decomposition of CaCO3
(b) Reactions involved in black and white photography
(c) Electrolysis of water
(d) burning of coal​

Answer 1

Answer:-

d) burning of coal

Burning of coal is combustion reaction which involves evolution of heat.

Any reaction which involves evolution of heat is said to be an exothermic reaction. Hence, this is not an endothermic reaction.

other reactions stated above are endothermic.

Decomposition reaction is Always endothermic.

Answer 2

Answer:

One of the earliest known humans is Homo habilis, or “handy man,” who lived about 2.4 million to 1.4 million years ago in Eastern and Southern Africa