Chemical test for positive ions

• What is a flame test?

  holding a hydrochloride acid dipped metal ion over a flame and seeing what colour the flame goes
• Lithium goes crimson, sodium goes yellow, potassium goes lilac, calcium goes orangish-red and copper goes green
• What is a precipitate?

  an insoluble solid formed by a reaction taking place in a solution
• Calcium chloride + sodium hydroxide ➡️ calcium hydroxide + sodium chloride
• How are aluminium ions distinguished from calcium & magnesium ions in a reaction with sodium hydroxide?

  aluminium dissolves