Uddeshya

A 400 kg. wooden log is floating with 0.2 of its volume above water level. Given that the density of iron is 7.8 gram per centimeter cubic, calculate the least mass of iron object attached to the underside of log that will sink it.

the first statement is true. there are reactions which require energy for activation and reaction proceeds with the evolution of energy. chemical bonds MIGHT NOT be always broken by energy absorption. the amount of energy depends on the nature of reactant...

Compounds are such substances that can't be separated by chemical means like potassium chloride, sodium chloride(common salt), potassium aluminium sulphate(alum).