Question 8 — Keerthi wrote a secret message to - Questions at the end of the chapter - Chapter 2 Class 7 - Exploring Substances: Acidic, Basic, and Neutral

Last updated at August 16, 2026 by

Q8 (Medium): Keerthi wrote a secret message to her grandmother on her birthday using orange juice. Can you assist her grandmother in revealing the message? Which indicator would you use to make it visible?

Answer:
We have studied that acidic substances like orange juice are invisible on paper but react with basic indicators . This is why we need a basic indicator spray.

  • Orange juice is acidic - invisible on paper
  • Spray baking soda solution (basic indicator)
  • Acid-base reaction makes writing visible
  • Colour change reveals the secret message
Revealing Secret Message Step 1 Orange juice (acidic) - invisible Step 2 Spray baking soda (basic) Step 3 Acid-base reaction occurs Message becomes visible!
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