CIE iGCSE Co-Ordinated Science C11.1 Formulas and terminology Exam Style Questions Paper 2
Question
What is a general formula for unsaturated hydrocarbons?
(A) $C_{n}H_{n+2}$
(B) $C_{2n}H_{2n+2}$
(C) $C_{n}H_{2n}$
(D) $C_{n}H_{2n+2}$
▶️Answer/Explanation
Ans: C
Question
The structure of a molecule of compound X is shown.
Which two formulas represent compounds that are in the same homologous series as X?
(A) C5H10 and C5H12
(B) C4H10 and C6H14
(C) C3H6 and C5H10
(D) C3H6 and C4H10
▶️Answer/Explanation
Ans : C
Question
The structures of three organic compounds are shown.
Which statement about these three compounds is correct?
A. They are alcohols.
B. They are alkenes.
C. They are saturated.
D. They do not burn.
▶️Answer/Explanation
Answer: C
Explanation: All three compounds shown are saturated hydrocarbons (alkanes) as they contain only single bonds between carbon atoms.
– They are not alcohols (no -OH group)
– They are not alkenes (no C=C double bonds)
– They do burn (alkanes are combustible)
The key feature is that they are saturated, meaning they contain the maximum possible number of hydrogen atoms with no double or triple bonds.
Question
Which diagram represents a molecule of ethane?
▶️Answer/Explanation
Answer: C
Explanation: Ethane (C₂H₆) is a saturated hydrocarbon with single bonds between all atoms. Option C correctly shows two carbon atoms single-bonded to each other and each bonded to three hydrogen atoms.