Online Test — Acids, Bases and Salts
25 Questions • 15 min • Chapter MCQ
15:00
Question 1 of 25
Acids generally taste:
Bitter
Sour
Salty
Sweet
Explanation: Acids characteristically taste sour, like lemon and vinegar.
Question 2 of 25
An acid turns litmus paper which colour?
Blue litmus red
Red litmus blue
Red litmus green
Blue litmus yellow
Explanation: Acids turn blue litmus paper red, the standard test for an acid.
Question 3 of 25
The acid present in vinegar is:
Citric acid
Acetic acid
Lactic acid
Tartaric acid
Explanation: Vinegar contains acetic acid, an organic acid.
Question 4 of 25
Which of these is a strong mineral acid?
Citric acid
Lactic acid
Sulphuric acid
Tartaric acid
Explanation: Sulphuric acid (H₂SO₄) is a strong, corrosive mineral acid.
Question 5 of 25
The acid produced in the human stomach to help digestion is:
Nitric acid
Hydrochloric acid
Acetic acid
Citric acid
Explanation: The stomach secretes dilute hydrochloric acid to aid digestion.
Question 6 of 25
Bases generally taste:
Sour
Bitter
Salty
Sweet
Explanation: Bases taste bitter and feel soapy, opposite to the sour taste of acids.
Question 7 of 25
A base turns litmus paper which colour?
Blue litmus red
Red litmus blue
Red litmus green
Blue litmus yellow
Explanation: Bases turn red litmus paper blue, the standard test for a base.
Question 8 of 25
A base that dissolves in water is called a/an:
Acid
Salt
Alkali
Indicator
Explanation: A base that dissolves in water is specifically called an alkali.
Question 9 of 25
Which substance is used in many antacids to relieve stomach acidity?
Sulphuric acid
Magnesium hydroxide
Citric acid
Sodium chloride
Explanation: Magnesium hydroxide, a mild base, neutralises excess stomach acid.
Question 10 of 25
Which of the following is a strong, corrosive base?
Baking soda
Lime water
Sodium hydroxide
Toothpaste
Explanation: Sodium hydroxide (NaOH) is a strong, corrosive base.
Question 11 of 25
A substance that changes colour to show if something is an acid or base is a/an:
Salt
Indicator
Alkali
Catalyst
Explanation: An indicator signals the acidic or basic nature of a substance by changing colour.
Question 12 of 25
Litmus is a natural dye obtained from:
Roses
Lichens
Turmeric
Cabbage
Explanation: Litmus is extracted from lichens.
Question 13 of 25
Phenolphthalein turns which colour in a basic solution?
Colourless
Pink
Red
Yellow
Explanation: Phenolphthalein is colourless in acids and turns pink in bases.
Question 14 of 25
Turmeric, a natural indicator, turns red in the presence of a:
Acid
Base
Salt
Neutral substance
Explanation: Turmeric is yellow in acid/neutral and turns red in a base.
Question 15 of 25
Methyl orange turns red in the presence of a/an:
Base
Acid
Salt
Alkali
Explanation: Methyl orange is red in acids and yellow in bases.
Question 16 of 25
The pH scale runs over the range of values from:
0 to 7
0 to 14
1 to 10
7 to 14
Explanation: The pH scale runs from 0 to 14, measuring acidity and basicity.
Question 17 of 25
A solution with a pH of exactly 7 is:
Strongly acidic
Neutral
Strongly basic
Weakly basic
Explanation: A pH of 7 is neutral, like pure water.
Question 18 of 25
A solution with a pH less than 7 is:
Acidic
Basic
Neutral
A salt
Explanation: A pH below 7 means the solution is acidic.
Question 19 of 25
As the pH value rises above 7, the solution becomes increasingly:
Acidic
Neutral
Basic
Sour
Explanation: Values above 7 are basic, and the higher the value, the stronger the base.
Question 20 of 25
Which solution is the strongest acid?
pH 6
pH 4
pH 2
pH 7
Explanation: The lower the pH below 7, the stronger the acid; pH 2 is the strongest here.
Question 21 of 25
The reaction between an acid and a base is called:
Oxidation
Neutralisation
Crystallisation
Corrosion
Explanation: An acid reacting with a base is a neutralisation reaction.
Question 22 of 25
The products formed in a neutralisation reaction are:
Salt and hydrogen
Salt and water
Acid and base
Water only
Explanation: Neutralisation produces a salt and water (with heat released).
Question 23 of 25
Common table salt is chemically known as:
Sodium hydroxide
Sodium chloride
Sodium sulphate
Calcium carbonate
Explanation: Common table salt is sodium chloride (NaCl).
Question 24 of 25
An antacid relieves stomach acidity because it is a mild:
Acid
Base
Salt
Indicator
Explanation: An antacid is a mild base that neutralises excess stomach acid.
Question 25 of 25
Acid rain is formed when rainwater dissolves polluting gases such as:
Oxygen and nitrogen
Sulphur and nitrogen oxides
Carbon and helium
Water vapour only
Explanation: Sulphur and nitrogen oxides from burning fuels dissolve in rain to form acid rain.