Home / iGCSE Chemistry (0620) Core:11.1 Formulae, functional groups and terminology: Exam Style Questions Paper 1

iGCSE Chemistry (0620) Core:11.1 Formulae, functional groups and terminology: Exam Style Questions Paper 1

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

Which statements about homologous series are correct?

  1. All carboxylic acids have similar chemical properties.
  2. All alcohols have the same molecular mass.
  3. Ethane and ethene are members of the same homologous series.
  4. Ethane and propane are members of the same homologous series.

A) 1 and 3
B) 1 and 4
C) 2 and 3
D) 2 and 4

▶️ Answer/Explanation
Solution

Ans: B

1. Correct – Members of a homologous series (like carboxylic acids) have similar chemical properties due to the same functional group.
2. Incorrect – Alcohols have different molecular masses (e.g., methanol CH3OH = 32, ethanol C2H5OH = 46).
3. Incorrect – Ethane (alkane) and ethene (alkene) are in different homologous series with different functional groups.
4. Correct – Ethane (C2H6) and propane (C3H8) are both alkanes in the same homologous series, differing by CH2.

Therefore, only statements 1 and 4 are correct.

Question

Which statement describes a homologous series?

A) a family of elements in the same group of the Periodic Table
B) a family of elements with similar chemical properties
C) a family of compounds with the same functional group
D) a family of compounds with similar physical properties

▶️ Answer/Explanation
Solution

Ans: C

A homologous series is a family of organic compounds that:

  • Have the same functional group
  • Show a gradual change in physical properties
  • Have similar chemical properties
  • Differ by a CH2 unit in their molecular formulae

Key points:

  • Option A describes groups in the Periodic Table, not homologous series
  • Option B is partially correct but too vague – it’s about compounds, not elements
  • Option D is partially correct but not the complete definition
  • Option C is the most accurate as the functional group defines the series (e.g., alcohols, alkanes)

Examples of homologous series include alkanes (CH4, C2H6, etc.) and alcohols (CH3OH, C2H5OH, etc.).

Question

 Which statement about members of a homologous series is correct?

A They are elements with the same chemical properties.

B They are compounds with the same functional group.

C They are atoms with the same number of outer electrons.

D They are molecules with the same boiling point.

▶️Answer/Explanation

Ans:B

A homologous series refers to a group of organic compounds that have the same general formula and similar chemical properties because they share the same functional group.

Question

The structure of an organic molecule is shown.

▶️Answer/Explanation

Ans: D

It has -OH (alcohol), C=C(alkene) and -COOH(carboxylic acid) functional groups. 

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