Home / iGCSE Chemistry (0620) Core:7.2 Oxides: Exam Style Questions Paper 1

iGCSE Chemistry (0620) Core:7.2 Oxides: Exam Style Questions Paper 1

iGCSE Chemistry (0620) Core Paper 1 - All Chapters
Question

Four different groups of oxides are shown.

  1. MgO   FeO   CuO
  2. CaO   SO2   TiO2
  3. PbO   CaO   Cl2O
  4. NO2   Br2O   P2O5

Which statement about these groups of oxides is correct?

A) 1, 2 and 3 contain basic oxides only.
B) 2, 3 and 4 contain basic oxides only.
C) 1 contains basic oxides only, and 4 contains acidic oxides only.
D) 1 contains acidic oxides only, and 4 contains basic oxides only.

▶️ Answer/Explanation
Solution

Ans: C

Analyzing each group’s oxide types:

1. MgO, FeO, CuO: All metal oxides → basic oxides (correct in option C)

2. CaO (basic), SO2 (acidic), TiO2 (amphoteric): Mixed properties

3. PbO (amphoteric), CaO (basic), Cl2O (acidic): Mixed properties

4. NO2, Br2O, P2O5: All non-metal oxides → acidic oxides (correct in option C)

Therefore, only statement C is completely correct: Group 1 contains only basic oxides (metal oxides) and Group 4 contains only acidic oxides (non-metal oxides). The other groups contain mixtures of oxide types.

Question

The diagram shows one period of the Periodic Table.

LiBeBCNOFNe

Which two elements form acidic oxides?

A) beryllium and lithium
B) carbon and neon
C) carbon and nitrogen
D) nitrogen and neon

▶️ Answer/Explanation
Solution

Ans: C

Acidic oxides are formed by non-metals. In the given period:

  • Lithium (Li) and Beryllium (Be) are metals that form basic oxides.
  • Neon (Ne) is a noble gas and doesn’t form oxides.
  • Carbon (C) forms CO2 and CO, both acidic oxides.
  • Nitrogen (N) forms several oxides like NO2 and N2O5, which are acidic.

Therefore, the correct pair is carbon and nitrogen (Option C).

Question

Which row identifies a basic oxide and describes an alkali?

 basic oxidedescription of an alkali
Asodium oxideinsoluble base
Bsodium oxidesoluble base
Csulfur dioxideinsoluble base
Dsulfur dioxidesoluble base
▶️ Answer/Explanation
Solution

Ans: B

Sodium oxide (Na2O) is a basic oxide because it reacts with acids to form salts and water. Basic oxides are typically formed by metals.

An alkali is specifically defined as a soluble base. Therefore, the correct description is “soluble base”.

Sulfur dioxide (SO2) is actually an acidic oxide, not basic, as it forms sulfurous acid when dissolved in water. This eliminates options C and D.

Between A and B, the key difference is the description of alkali. Since alkalis are soluble bases, option B is correct.

Question

 Oxides of nitrogen are given out from car exhausts.
Which row best shows why oxides of nitrogen are unwanted in the atmosphere?

▶️Answer/Explanation

Ans:D

When fuel is burned in an internal combustion engine, such as in cars, nitrogen and oxygen from the air combine under high temperatures to form various oxides of nitrogen, primarily nitrogen monoxide (NO) and nitrogen dioxide (NO2). These gases are collectively referred to as NOx.

Nitrogen dioxide is a particularly harmful component of NOx. It is a reddish-brown gas with a pungent odor. NO2 can cause respiratory problems, irritation of the respiratory system, and contribute to the development or exacerbation of conditions such as asthma and other lung diseases. It can also have negative environmental impacts on plants and ecosystems.

Furthermore, NOx gases contribute to the formation of nitric acid in the atmosphere, which is a corrosive and environmentally harmful acid. Nitric acid can damage buildings, infrastructure, and vegetation when it falls as acid rain.

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