ICSE 8th Chemistry: Language of Chemistry Practice Questions
Welcome to our comprehensive set of practice questions for the "Language of Chemistry" chapter. Test your knowledge across a variety of question formats!
Section 1: Multiple Choice Questions
Question 1:
The symbol for the element Gold is:
- So
- Au
- Ag
- Gd
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Answer: b) Au
Question 2:
A group of atoms that behaves as a single unit is called a/an:
- Molecule
- Ion
- Polyatomic ion
- Element
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Answer: c) Polyatomic ion
Question 3:
The valency of the sulphate ($SO_4$) radical is:
- +2
- -1
- -2
- +1
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Answer: c) -2
Question 4:
The chemical formula for water is:
- H2O2
- HO
- H2O
- OH
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Answer: c) H2O
Question 5:
The Latin name for the element Lead is:
- Natrium
- Cuprum
- Ferrum
- Plumbum
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Answer: d) Plumbum
Section 2: Fill in the Blanks
Question 6:
The process of a solid turning directly into a gas is called ____________.
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Answer: Sublimation
Question 7:
The valency of an element is its ____________ power.
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Answer: combining
Question 8:
The number of atoms present in a molecule of an element is known as its ____________.
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Answer: atomicity
Question 9:
The subscript number in a chemical formula indicates the number of ____________.
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Answer: atoms
Question 10:
A chemical equation must always be ____________ to satisfy the law of conservation of mass.
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Answer: balanced
Section 3: Name the Following
Question 11:
An element that is a liquid at room temperature and is a non-metal.
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Answer: Bromine
Question 12:
The symbol for the element Potassium.
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Answer: K
Question 13:
The smallest particle of an element that can take part in a chemical reaction.
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Answer: Atom
Question 14:
A molecule consisting of two atoms of the same element.
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Answer: Diatomic molecule
Question 15:
The chemical symbol derived from the Latin name 'Stannum'.
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Answer: Sn (Tin)
Section 4: Match the Pair
Question 16:
| Column A | Column B |
|---|---|
| 1. Hydrogen | a. Noble gas |
| 2. Carbon Dioxide | b. Non-metal |
| 3. Neon | c. Greenhouse gas |
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Answer: 1-b, 2-c, 3-a
Question 17:
| Column A | Column B |
|---|---|
| 1. Atomicity of Phosphorus | a. 1 |
| 2. Atomicity of Sulphur | b. 4 |
| 3. Atomicity of Argon | c. 8 |
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Answer: 1-b, 2-c, 3-a
Question 18:
| Column A | Column B |
|---|---|
| 1. Ferrous | a. Fe3+ |
| 2. Ferric | b. Fe2+ |
| 3. Sulphide | c. S2- |
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Answer: 1-b, 2-a, 3-c
Question 19:
| Column A | Column B |
|---|---|
| 1. Ammonium | a. OH- |
| 2. Hydroxide | b. NO3- |
| 3. Nitrate | c. NH4+ |
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Answer: 1-c, 2-a, 3-b
Question 20:
| Column A | Column B |
|---|---|
| 1. Valency of Copper (I) | a. 2 |
| 2. Valency of Magnesium | b. 1 |
| 3. Valency of Calcium | c. 2 |
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Answer: 1-b, 2-a, 3-c
Section 5: Name the Compound / Make the Formula
Question 21:
Write the chemical formula for Calcium Sulphate.
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Answer: CaSO4
Question 22:
Write the chemical name for H2SO4.
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Answer: Sulphuric acid
Question 23:
Write the chemical formula for Sodium Carbonate.
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Answer: Na2CO3
Question 24:
Write the chemical name for HNO3.
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Answer: Nitric acid
Question 25:
Write the chemical formula for Ammonium Chloride.
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Answer: NH4Cl
Section 6: Write Balanced Equation (1 Mark Each)
Question 26:
Balance the following chemical equation:
Unbalanced: N2 + H2 → NH3
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Balanced Equation: N2 + 3H2 → 2NH3
Question 27:
Balance the following chemical equation:
Unbalanced: Fe + Cl2 → FeCl3
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Balanced Equation: 2Fe + 3Cl2 → 2FeCl3
Question 28:
Balance the following chemical equation:
Unbalanced: C + O2 → CO2
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Balanced Equation: C + O2 → CO2 (This equation is already balanced.)
Question 29:
Balance the following chemical equation:
Unbalanced: CH4 + O2 → CO2 + H2O
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Balanced Equation: CH4 + 2O2 → CO2 + 2H2O
Question 30:
Balance the following chemical equation:
Unbalanced: Al + O2 → Al2O3
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Balanced Equation: 4Al + 3O2 → 2Al2O3
Question 31:
Balance the following chemical equation:
Unbalanced: Fe2O3 + H2 → Fe + H2O
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Balanced Equation: Fe2O3 + 3H2 → 2Fe + 3H2O
Question 32:
Balance the following chemical equation:
Unbalanced: P4 + O2 → P4O10
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Balanced Equation: P4 + 5O2 → P4O10
Question 33:
Balance the following chemical equation:
Unbalanced: KOH + H2SO4 → K2SO4 + H2O
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Balanced Equation: 2KOH + H2SO4 → K2SO4 + 2H2O
Question 34:
Balance the following chemical equation:
Unbalanced: C2H6 + O2 → CO2 + H2O
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Balanced Equation: 2C2H6 + 7O2 → 4CO2 + 6H2O
Question 35:
Balance the following chemical equation:
Unbalanced: Mg + HNO3 → Mg(NO3)2 + H2
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Balanced Equation: Mg + 2HNO3 → Mg(NO3)2 + H2
Section 7: General Questions (3 Marks Each)
Question 36: Define with Example (3 Marks)
Define **Valency** with a suitable example.
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Answer: Valency is the **combining capacity** of an element. It is the number of hydrogen atoms with which one atom of the element combines. For example, in water (H2O), two hydrogen atoms combine with one oxygen atom, so the valency of oxygen is 2.
Question 37: Give Reason (3 Marks)
Give a reason why chemical equations need to be balanced.
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Answer: Chemical equations must be balanced to obey the **Law of Conservation of Mass**, which states that matter cannot be created or destroyed in a chemical reaction. Balancing an equation ensures that the number of atoms of each element on the reactant side is equal to the number of atoms of that same element on the product side.
Question 38: Information from an Equation (3 Marks)
What information can you get from the balanced chemical equation: 2H2(g) + O2(g) → 2H2O(l)?
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Answer: This balanced equation tells us that:
- Two molecules of hydrogen gas (H2) react with one molecule of oxygen gas (O2).
- They combine to form two molecules of water (H2O).
- The reactants, hydrogen and oxygen, are in the gaseous state (g).
- The product, water, is in the liquid state (l).
Question 39: List Formula and Names (3 Marks)
Give the chemical formula and name for three common polyatomic ions.
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Answer:
- **Sulphate:** SO42-
- **Carbonate:** CO32-
- **Ammonium:** NH4+
Question 40: Why This Happened (3 Marks)
Explain why the formula for Sodium Sulphide is Na2S, and not NaS or NaS2.
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Answer: The formula is Na2S because it is based on the valencies of the constituent elements. The valency of Sodium (Na) is 1, and the valency of Sulphur (S) is 2. To form a neutral compound, two atoms of Sodium (2 x 1 = 2) are needed to combine with one atom of Sulphur (1 x 2 = 2) to balance the charges, following the criss-cross method.
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