Identification of Ions — Flame Tests and Precipitates Quiz
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5 questions, one answer each
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1. What flame colour is produced by potassium ions?
- A. Crimson
- B. Yellow
- C. Lilac
- D. Green
2. Which precipitate colour indicates copper(II) ions when sodium hydroxide is added?
- A. White
- B. Blue
- C. Green
- D. Brown
3. What gas is produced when a carbonate reacts with dilute acid, and how is it identified?
- A. Oxygen; relights a glowing splint
- B. Hydrogen; squeaky pop with a lit splint
- C. Carbon dioxide; turns limewater milky
- D. Chlorine; bleaches damp litmus paper
4. A student adds sodium hydroxide to an unknown solution and gets a white precipitate. Adding excess sodium hydroxide dissolves it. Which ion is present?
- A. Calcium
- B. Magnesium
- C. Aluminium
- D. Copper
5. A forensic scientist has an unknown white solid and wants to identify both the metal ion and an anion precisely and quickly, minimising the amount of sample used. Which approach best fits this need, and why?
- A. Chemical tests only, because they use larger sample quantities for reliability
- B. An instrumental method such as flame emission spectroscopy, because instrumental methods are accurate, sensitive and rapid
- C. A flame test only, because it works for all types of ions including anions
- D. No analysis is possible without a diagram of the crystal structure