Core5 mapped NDA questions
Build the idea
Build exam-ready understanding by connecting the core idea, formulas or facts, worked example and previous NDA questions. Focus on why each rule works, then test it under timed conditions.
Concept
Acids taste sour and turn blue litmus red; bases taste bitter, feel soapy and turn red litmus blue. A salt is formed when an acid reacts with a base (neutralisation).
The pH scale (0–14) measures acidity/alkalinity.
Key Points & Formulas
- Acid + Base → Salt + Water (neutralisation).
- pH < 7 acidic, pH = 7 neutral, pH > 7 basic.
- Litmus: acids turn blue→red; bases turn red→blue.
- Common salt is NaCl; baking soda is NaHCO₃.
Worked Example
Q. What is formed when hydrochloric acid reacts with sodium hydroxide?
This is a neutralisation reaction.
HCl + NaOH → NaCl + H₂O.
Products are common salt (NaCl) and water.