Q22 of 44 Page 5

Which among the following changes are exothermic or endothermic in nature?

(a) Decomposition of ferrous sulphate


(b) Dilution of sulphuric acid


(c) Dissolution of sodium hydroxide in water


(d) Dissolution of ammonium chloride in water

(a) Decomposition of ferrous sulphate is an endothermic reaction because heat is absorbed from the environment during the reaction.


(b) Dilution of sulphuric acid is an exothermic reaction because heat is released into the environment during the reaction.


(c) Dissolution of sodium hydroxide in water is an exothermic reaction because heat is released into the environment during the reaction.in water.


(d) Dissolution of ammonium chloride in water is an endothermic reaction because heat is absorbed from the environment during the reaction.


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20

Write the balanced chemical equation for the following reactions and identify the type of reaction in each case.

(a) In Thermite reaction, iron (III) oxide reacts with aluminium and gives molten iron and aluminium oxide.


(b) Magnesium ribbon is burnt in an atmosphere of nitrogen gas to form solid magnesium nitride


(c) Chlorine gas is passed in an aqueous potassium iodide solution to form potassium chloride solution and solid iodine.


(d) Ethanol is burnt in air to form carbon dioxide, water and releases heat.

 21

Complete the missing components/variables given as X and Y in the following.

(a) Pb(NO3)2 (aq)+ 2Kl(aq) Pbl2 (X) + 2KNO3 (Y)


(b) Cu(s)+2AgNO3 (aq) Cu(NO3)2 (aq)+X(s)


(c) Zn(s) +H2SO4(aq)ZnSO4 (x) + H2(y)


(d) CaCO3(s) CaO(s)+CO2(g)

 23

Identify the reducing agent in the following reactions.

(a) 4NH3 + 5O24NO+6H2O


(b) H2O +F2HF + HOF


(c) Fe2O3 + 3CO2Fe + 3CO2


(d) 2H2 + O22H2O

 24

Identify the oxidising agent (oxidant) in the following reactions

(a) Pb3O4 + 8HCl ⎯→ 3PbCl2 + Cl2 + 4H2O


(b) 2Mg + O2⎯→ 2MgO


(c) CuSO4 + Zn ⎯→ Cu + ZnSO4


(d) V2O5 + 5Ca ⎯→ 2V + 5CaO


(e) 3Fe + 4H2 O ⎯→ Fe3O4 + 4H2


(f) CuO + H2⎯→ Cu + H2O