Form 4 - Acid and Base

Which statement is correct about acid?

• Acid solution conducts electric current

• Strong acid ionizes partially in water

• Weak acid produces high concentration of hydrogen ions

• The presence of water enables acid to produce hydroxide ions

Which substance is an alkali?

• Zinc oxide

• Magnesium oxide

• Potassium hydroxide

• Aluminium hydroxide

Table above shows the pH values of two solutions with the same concentration.

Which statement explains the differences in the pH values?

• Q ionizes partially whereas R ionizes completely

• The concentration of hydrogen ions in Q is lower than R

• The number of mole of hydrogen ions in Q is less than R

• The degree of ionization of Q is higher than R

Which acid contains the highest number of hydrogen ions?

• 25 cm³ of 1 mol dm^-3 nitric acid

• 25 cm³ of 1 mol dm^-3 ethanoic acid

• 25 cm³ of 1 mol dm^-3 sulphuric acid

• 25 cm³ of 1 mol dm^-3 hydrochloric acid

Diagram above shows two beakers, P and Q that contain granulated limestones, CaCO₃ and pH paper respectively in dilute ethanoic acid.

Which observation is correct?

• Gas bubble is released in beaker P and pH value in beaker Q is 1

• Gas bubble is released in beaker P and pH value in beaker Q is 4

• Solution turns cloudy in beaker P and pH value in beaker Q is 4

• There is no change in beaker P and pH value in beaker Q is 1

pH is a measure of

• hydrogen concentration

• hydroxide concentration

• hydrogen ion concentration

• hydroxide ion concentration

Which of the following is the correct sequence in preparation of a solution by dilution method?

I Transfer the solution into a volumetric flask

II Calculate the volume of solution to be diluted

III Use a pipette to obtain the volume of solution needed

IV Add distilled water to the required volume of solution

• II, I, III, IV

• II, I, IV, III

• II, III, I, IV

• II, III, IV, I

The following equation represents the reaction between hydrochloric acid and calcium hydroxide solution.

2HCl(aq) + Ca(OH)₂(aq) → CaCl₂(aq) + H2O(l)

20 cm³ of 0.1 mol dm^-3 hydrochloric acid is neutralised by 50 cm³ of calcium hydroxide solution.

What is the molarity of calcium hydroxide solution?

• 0.02 mol dm^-3

• 0.04 mol dm^-3

• 0.125 mol dm^-3

• 0.25 mol dm^-3

Which of the following is correct about weak alkaline solution?

• Have pH value of 13

• Partially ionised in water

• Concentration of the solution is low

• Solution does not react with acid

What is the number of moles in 100 cm³ of 1.5 mol dm^-3 of nitric acid?

• 0.015 mol

• 0.100 mol

• 0.150 mol

• 1.500 mol