Question

state reasons for the following; a. iron articles get coated with a reddish brown powder when left for sometime in open. b. burning of coal is an exothermic reaction. c. the chemical equation should be balanced.

Answer 1

A.Rusting. because if metal is kept out for a long period of time it reacts with oxygen and moisture present in the atmosphere to form a reddish brown substance called rust
B. Because large amount of heat is evolved.
C. According to the conservation of mass , the number of molecules must be equal of both the sides of a equation.

Answer 2

Hey hope it helps

a. iron reacts with oxygen and moisture present in water so it becomes iron oxide which is reddish brown in colour

b. burning coal is considered as an exothermic reaction because it releases heat

c.this is according to the law of conservation of mass so obviously both the sides of the equation should be balanced