Q7 of 44 Page 1

Which among the following (are) double displacement reaction (s)?

(i) Pb + CuCl2 PbCl2+Cu


(ii) Na2SO4+BaCl2BaSO4+2NaCl


(iii) C+O2CO2


(iv) CH4+2O2CO2+2H2O

Double displacement reactions are such chemical reactions in which one component of each reactant exchange to form products. The cations and anions of two compounds exchange their ions to form two new compounds. Here only in reaction (ii), ions of both reactants are exchanged and two entirely different compounds are formed.


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5

Three beakers labelled as A, B and C each containing 25 mL of water were taken. A small amount of Na0H, anhydrous CuSO2 and NaCl were added to the beakers A, B and C respectively. It was observed that there was an increase in the temperature of the solutions contained in beakers A and B, whereas in case of beaker C, the temperature of the solution falls. Which one of the following statement (s) is (are) correct?

1. In beakers A and B, exothermic process has occurred.


2. In breakers A and B, endothermic process has occurred.


3. In breaker C, exothermic process has occurred.


4. In beaker C, endothermic process has occurred.

 6

A dilute ferrous sulphate solution was gradually added to the beaker containing acidified permanganate solution. The light purple colour of the solution fades and finally disappears. Which of the following is the correct explanation for the observation?

 8

Which among the following statement (s) is (are) true? Exposure of silver chloride to sunlight for a long duration turns grey due to

(i) the formation of silver by decomposition of silver chloride.


(ii) sublimation of silver chloride.


(iii) decomposition of chlorine gas from silver chloride.

 9

Solid calcium oxide reacts vigorously with water to form calcium hydroxide accompanied by the liberation of heat. This process is called slaking of lime water. Which among the following is/are true about slaking of lime water and the solution formed?

(i) It is an endothermic reaction.


(ii) It is exothermic reaction.


(iii) The pH of the resulting solution will be more than seven.


(iv)The pH of the resulting solution will be less than seven.