8th Chemical reactions

Question:  1-Define the following terms- (Write equations to support your answer)

i. Chemical reaction

ii. Exothermic reaction

iii. Decomposition reaction

iv. Oxidation reaction

Question:  2- Write down two characteristics of chemical reaction.

Question:  3- Balance the following equations-

(i) H2 + O 2 à H2O

(ii) Mg + O2 à MgO

(iii) N2 + H2 àNH3

(iv) H2S + Cl2 àS + HCl

Question:  4- Write the formula of the following-

(i) Magnesium hydroxide

(ii) Sodium carbonate

(iii) Silver nitrate

(iv) Iron sulphate

Question: 5- Fill in the blanks-

(i) When two chemicals in a solution form react, and an insoluble substance is formed and settles down in the form of __________.

(ii) Heat is absorbed in _____________ reactions.

(iii) The formula of rust is _________.