How do you classify the society on the basis of economy write one characteristic of any two of them

Explanation:

(1) The primary industry is mainly agriculture, which includes agricultural, forestry, animal husbandry and fishery components. Agriculture is the foundation of social economy. (2) The secondary industry, which mainly includes the industrial and construction industries.

a chemical reaction happens

explanation:

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.