CIE iGCSE Co-Ordinated Science C2.1 Elements, compounds and mixtures Exam Style Questions Paper 1
▶️ Answer/Explanation
The formula \(\mathrm{C_2H_5OH}\) contains three different chemical symbols: C (carbon), H (hydrogen), and O (oxygen). Although there are multiple atoms of carbon and hydrogen, they are the same elements. Therefore, ethanol contains 3 different elements in total.
✅ Answer: (B)
✅ Answer: (B)
▶️ Answer/Explanation
Carbon and sulfur are elements because they consist of only one type of atom. Potassium nitrate (KNO₃) is a compound because it contains potassium, nitrogen, and oxygen atoms chemically combined. Therefore, the mixture contains one compound and two elements.
✅ Answer: (A)
✅ Answer: (A)
▶️ Answer/Explanation
A compound is a substance made up of two or more different types of atoms chemically bonded together. Elements can exist as molecules (e.g. O₂) – they are not always single atoms. Mixtures can be separated by physical methods, not only chemical ones. Electrolysis is used for compounds, not mixtures of elements.
✅ Answer: (A)
✅ Answer: (A)
▶️ Answer/Explanation
NaOH contains three different elements: sodium (Na), oxygen (O) and hydrogen (H).
Rb\(_{2}\)S, SiCl\(_{4}\) and SnO\(_{2}\) each contain only two different elements, regardless of how many atoms of each are present.
Counting unique element symbols, not subscript numbers, shows NaOH has the most distinct elements.
✅ Answer: (A)
Rb\(_{2}\)S, SiCl\(_{4}\) and SnO\(_{2}\) each contain only two different elements, regardless of how many atoms of each are present.
Counting unique element symbols, not subscript numbers, shows NaOH has the most distinct elements.
✅ Answer: (A)
▶️ Answer/Explanation
Each mineral’s formula is checked element by element against the Periodic Table to classify each as a metal or non-metal.
Metals are mostly found on the left and centre of the Periodic Table, while non-metals are on the right.
Only one listed mineral has all three of its elements positioned among the non-metals.
✅ Answer: (C)
Metals are mostly found on the left and centre of the Periodic Table, while non-metals are on the right.
Only one listed mineral has all three of its elements positioned among the non-metals.
✅ Answer: (C)