1.
Which of the following statement is not true of dilute hydrochloric acid?
Correct Answer
A. It liberates ammonia gas from ammonium chloride on warming
Explanation
Dilute hydrochloric acid does not liberate ammonia gas from ammonium chloride on warming. This is because ammonium chloride is a stable compound and does not decompose into ammonia gas and hydrochloric acid upon heating.
2.
Y is heated with aqueous sodium hydroxide and ammonia gas is formed.
Y is ________.
Correct Answer
C. Ammonium sulpHate
Explanation
When Y is heated with aqueous sodium hydroxide, it reacts to form ammonia gas. This suggests that Y contains an ammonium compound. Among the given options, ammonium sulphate is the only compound that contains ammonium (NH4+) ions. Therefore, Y is most likely ammonium sulphate.
3.
Lake Y's water has a pH value of 3. Which substance could be added in to neutralise the pH value of the acidic water present without leaving an alkaline solution.
Correct Answer
B. Calcium carbonate
Explanation
Calcium carbonate is a basic compound that can be added to neutralize the acidic water in Lake Y. When calcium carbonate reacts with the acidic water, it releases carbon dioxide gas and forms calcium ions and bicarbonate ions. The bicarbonate ions act as a buffer, helping to maintain a neutral pH. Unlike the other options, calcium carbonate does not leave an alkaline solution because it reacts with the acid to form a neutral solution.
4.
Which of the following is true?
The strength of an acid depends on:
Correct Answer
D. It's degree of ionisation in water
Explanation
The strength of an acid depends on its degree of ionization in water. This means that a strong acid will completely ionize in water, while a weak acid will only partially ionize. The concentration, pH, and solubility of an acid are not indicators of its strength.
5.
Which one of the following burns in air to form an oxide which, when shaken with water, gives a solution with a pH greater than 7?
Correct Answer
D. Calcium
Explanation
Calcium burns in air to form calcium oxide (CaO). When shaken with water, calcium oxide reacts to form calcium hydroxide (Ca(OH)2), which is a strong base. A solution with a pH greater than 7 is considered basic, so calcium is the correct answer.
6.
Which of the following is a soluble base?
Correct Answer
C. Sodium hydroxide
Explanation
Sodium hydroxide is a soluble base because it dissolves in water to form hydroxide ions (OH-) which can accept protons (H+) to neutralize acids.
7.
Which of the following is a reaction observable from this reaction.
H2SO4 (aq) + CuCO3 (s) --> H2O (l) + CO2 (g) + CuSO4 (aq)
Correct Answer
B. Copper(II) carbonate reacts with the acid and disappears, forming a blue solution
Explanation
The given reaction involves the reaction between copper(II) carbonate (CuCO3) and sulfuric acid (H2SO4). The observation of a blue solution indicates that copper(II) carbonate reacts with the acid and disappears, forming a blue solution. This is a clear indication of a chemical reaction occurring between the two compounds.
8.
When two liquids are mixed, a solution with a value of pH 7 is formed. Which of the following are the pH values of the two liquids.
Correct Answer
B. 1st: pH 5, 2nd: pH 12
Explanation
The correct answer is 1st: pH 5, 2nd: pH 12. This is because when two liquids with different pH values are mixed, the resulting pH of the solution depends on the concentration of hydrogen ions (H+) and hydroxide ions (OH-) in the solution. A pH of 7 is considered neutral, indicating an equal concentration of H+ and OH-. A pH value below 7 indicates acidity, while a pH value above 7 indicates alkalinity. In this case, the first liquid with a pH of 5 is acidic, and the second liquid with a pH of 12 is alkaline. When mixed together, the acidity of the first liquid and the alkalinity of the second liquid neutralize each other, resulting in a pH of 7 for the solution.