CIE iGCSE Co-Ordinated Science C11.1 Formulas and terminology Exam Style Questions Paper 1
▶️ Answer/Explanation
Counting the atoms in the displayed structure: there are 4 carbon atoms (four vertices or ends), 8 hydrogen atoms (from the bonds around each carbon), and 2 oxygen atoms. Thus the molecular formula is \(\mathrm{C_4H_8O_2}\).
✅ Answer: (D)
✅ Answer: (D)
▶️ Answer/Explanation
To find the molecular formula, count each type of atom in the displayed structure: 4 carbon atoms, 6 hydrogen atoms, and 3 oxygen atoms.
This gives the molecular formula \(\text{C}_4\text{H}_6\text{O}_3\), which corresponds to option C.
✅ Answer: (C)
This gives the molecular formula \(\text{C}_4\text{H}_6\text{O}_3\), which corresponds to option C.
✅ Answer: (C)
▶️ Answer/Explanation
An unsaturated compound contains one or more carbon–carbon bonds that are not single bonds.
Ethene, \( \text{C}_2\text{H}_4 \), contains a carbon–carbon double bond, so it is unsaturated.
Ethane, ethanol and methane all have only single carbon–carbon (or no carbon–carbon) bonds, making them saturated.
✅ Answer: (C)
Ethene, \( \text{C}_2\text{H}_4 \), contains a carbon–carbon double bond, so it is unsaturated.
Ethane, ethanol and methane all have only single carbon–carbon (or no carbon–carbon) bonds, making them saturated.
✅ Answer: (C)
▶️ Answer/Explanation
Row A actually shows ethene (C=C double bond), not methane, and row B shows ethanol (with –OH), not ethene, so both are mislabelled.
Row C correctly shows the saturated two-carbon structure \( C_2H_6 \) labelled as ethane, matching its structure and name.
✅ Answer: (C)
Row C correctly shows the saturated two-carbon structure \( C_2H_6 \) labelled as ethane, matching its structure and name.
✅ Answer: (C)
▶️ Answer/Explanation
A hydrocarbon contains only carbon and hydrogen, which rules out option D since it contains oxygen.
The ratio of H atoms to C atoms must be exactly 3:1; checking each remaining formula, only \(C_2H_6\) gives \( \frac{6}{2} = 3 \).
✅ Answer: (C)
The ratio of H atoms to C atoms must be exactly 3:1; checking each remaining formula, only \(C_2H_6\) gives \( \frac{6}{2} = 3 \).
✅ Answer: (C)