Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 980 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) chemical (d) musical
2. 2.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) it turned into air (d) dry juice is see-through
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
5. 5.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) lemon juice (d) a mirror
7. 7.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if cooled (d) yes, if shaken
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) yeast (d) an adult with an iron
9. 9.🔍 Which is the odd one out? (a) writing the message (b) cutting the lemon (c) dipping the cotton bud (d) reading the message
10. 10.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) the paper floats (c) writing turns green (d) it gets darker
11. 11.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) paper turns lemony (d) the juice scorches first
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
13. 13.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
14. 14.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) plugging in the iron (c) ironing the paper (d) cutting the lemon
15. 15.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
16. 16.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) white paper (d) a magnet
18. 18.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the kind of juice (c) the iron setting (d) how dark the writing is
20. 20.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) dipping the cotton bud (d) plugging in the iron
21. 21.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) almost nothing (d) a rainbow
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) turmeric powder (c) lemon juice (d) yeast
23. 23.True or false: yeast is needed for the secret lemon message. (a) False (b) True
24. 24.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) turmeric powder (c) white paper (d) a battery cell
26. 26.True or false: reading the message is a job for an adult. (a) True (b) False
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) yeast (d) an adult with an iron
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) a mirror (d) lemon juice
29. 29.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) yeast (d) an adult with an iron
30. 30.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) reading the message (d) plugging in the iron
31. 31.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) dipping the cotton bud (d) putting the iron away
32. 32.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is magnetic (d) it is cold
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the ironing time (c) the same cotton bud (d) the kind of juice
34. 34.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
35. 35.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
36. 36.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) ironing the paper (d) letting the paper dry
37. 37.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
38. 38.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
39. 39.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) skip washing (d) wash your hands
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) lemon juice (c) a small bowl (d) a cotton bud

Free science experiments lessons, practice and worksheets at talentjr.in/science-experiments-for-kids