Anil Ahlawat Solutions for Chapter: Chemical Reactions and Equations, Exercise 2: EXERCISES

Which of the following reactions are exothermic in nature?

(i) Evaporation of water

(ii) Dissolution of sodium hydroxide in water

(iii) Dilution of sulphuric acid

(iv) Dissolution of ammonium chloride in water

(v) Combustion of methane gas

Marble chips or calcium carbonate react with hydrochloric acid as:

${\mathrm{CaCO}}_3+2\mathrm{HCl} \to {\mathrm{CaCl}}_2+{\mathrm{H}}_2\mathrm{O}+{\mathrm{CO}}_2$

The reaction is carried out twice and the following graphs were obtained:

Which of the following statements is incorrect?

Four students P, Q, R and S noted the initial colour of the solutions kept in beakers I, II, III and IV. After inserting zinc rods in each solution and leaving them undisturbed for two hours, the colour of each solution was again noted in the form of the table given below:

Which student noted the colour change in all the four beakers correctly?

Observe the given figure carefully. Which of the following observation(s) is/are correct?

I. A double decomposition reaction takes place.

II. Brown fumes of ${\mathrm{NO}}_2$are evolved.

III. Red residue is left behind in the test tube.

Rupali, a class $10$student has set up the apparatus as shown in the figures.

Which of the following observations is correct?