10 Question MCQ (including Assertion)

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
(iv) oxidation of silver chloride

Assertion (A): After white washing the walls, a shiny white finish on walls is obtained after two to  three days.  
Reason (R): Calcium oxide reacts with carbon  dioxide to form calcium hydrogen carbonate  which gives a shiny white finish.

Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is

Assertion (A): A chemical reaction becomes faster at higher temperatures.  
Reason (R):  At higher temperatures, molecular  motion becomes more rapid.

Which of the following are combination reactions?
(i) \(2 \mathrm{KClO}_3 \xrightarrow{\text { Heat }} 2 \mathrm{KCl}+3 \mathrm{O}_2\)
(ii) \(\mathrm{MgO}+\mathrm{H}_2 \mathrm{O} \longrightarrow \mathrm{Mg}(\mathrm{OH})_2\)
(iii) \(4 \mathrm{Al}+3 \mathrm{O}_2 \longrightarrow 2 \mathrm{Al}_2 \mathrm{O}_3\)
(iv) \(\mathrm{Zn}+\mathrm{FeSO}_4 \longrightarrow \mathrm{ZnSO}_4+\mathrm{Fe}\)

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?

The following reaction is used for the preparation of oxygen gas in the laboratory

$$ 2 \mathrm{KClO}_3(\mathrm{~s}) \xrightarrow[\text { Catalyst }]{\text { Heat }} 2 \mathrm{KCl}(\mathrm{~s})+3 \mathrm{O}_2(\mathrm{~g}) $$

Which of the following statement(s) is(are) correct about the reaction?

Which of the following gases can be used for storage of fresh samples of an oil for a long time?

Solid calcium oxide reacts vigorously with water to form calcium hydroxide accompanied by liberation of heat. This process is called slaking of lime. Calcium hydroxide dissolves in water to form its solution called lime water. Which among the following is (are) true about slaking of lime and the solution formed?
(i) It is an endothermic reaction
(ii) It is an 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