AQA GCSE Chemistry Topic 1 Verified Answers
1. What is the smallest unit of an element that can exist on its own?
Answer: Atom.
2. What is a chemical bond between two or more elements?
Answer: Compound.
3. What is a combination of two or more elements or compounds that are not chemically bonded?
Answer: Mixture.
4. What is the sum of protons and neutrons in an atom?
Answer: Relative mass.
5. What do you use to draw the line for chromatography?
Answer: Pencil.
6. What does chromatography separate, and why?
Answer: Chromatography separates inks because dyes move at different rates.
7. Why must the solvent start below the ink in chromatography?
Answer: The solvent must start below the ink to avoid ink dissolving.
, 8. What stays at the baseline in chromatography, and why?
Answer: Insoluble dyes stay at the baseline because they do not move with the solvent.
9. Where do you measure the distance for rf values?
Answer: You measure the distance from the middle of the spot.
10. What is used to calculate rf values?
Answer: The substance distance divided by the solvent distance equals rf.
11. What is used to separate insoluble solids from liquids?
Answer: Filtration uses filter paper to separate insoluble solids from liquids.
12. What process separates soluble solids from solutions if they don't decompose?
Answer: Evaporation separates soluble solids from solutions if they don't decompose.
13. What is used to separate a salt that decomposes in solution?
Answer: Crystallization separates a salt that decomposes in solution by removing heat once salts start to
form.
14. How do you separate rock salt?
1. What is the smallest unit of an element that can exist on its own?
Answer: Atom.
2. What is a chemical bond between two or more elements?
Answer: Compound.
3. What is a combination of two or more elements or compounds that are not chemically bonded?
Answer: Mixture.
4. What is the sum of protons and neutrons in an atom?
Answer: Relative mass.
5. What do you use to draw the line for chromatography?
Answer: Pencil.
6. What does chromatography separate, and why?
Answer: Chromatography separates inks because dyes move at different rates.
7. Why must the solvent start below the ink in chromatography?
Answer: The solvent must start below the ink to avoid ink dissolving.
, 8. What stays at the baseline in chromatography, and why?
Answer: Insoluble dyes stay at the baseline because they do not move with the solvent.
9. Where do you measure the distance for rf values?
Answer: You measure the distance from the middle of the spot.
10. What is used to calculate rf values?
Answer: The substance distance divided by the solvent distance equals rf.
11. What is used to separate insoluble solids from liquids?
Answer: Filtration uses filter paper to separate insoluble solids from liquids.
12. What process separates soluble solids from solutions if they don't decompose?
Answer: Evaporation separates soluble solids from solutions if they don't decompose.
13. What is used to separate a salt that decomposes in solution?
Answer: Crystallization separates a salt that decomposes in solution by removing heat once salts start to
form.
14. How do you separate rock salt?
