A student attempted to prepare potassium chloride crystals from the mixture of 20 cm³ potassium hydroxide and 35 cm³ hydrochloric acid. Small amounts of charcoal were added to the mixture and then removed. The solution was then heated to dryness.

1. aExplain the purpose of adding charcoal. [1]
2. bHow was the charcoal removed? [1]
3. cWhat is the colour of the solid which remained? [1]
4. dWere the crystals obtained pure? Explain. [1]
5. eGive one application of acid-base reactions in daily life. [1]

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