Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 377 · 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) chemical (b) physical (c) magnetic (d) musical
2. 2.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) ironing the paper (d) reading the message
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) yeast (c) a small bowl (d) lemon juice
4. 4.True or false: ironing the paper is a job a child can do. (a) True (b) False
5. 5.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing stays faint (c) writing turns green (d) it gets darker
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we change it (c) we measure it
7. 7.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) ironing the paper (d) letting the paper dry
8. 8.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands
9. 9.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) dipping the cotton bud (c) ironing the paper (d) putting the iron away
10. 10.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
11. 11.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a balloon (c) a mirror (d) lemon juice
12. 12.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
13. 13.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
14. 14.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
15. 15.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) dipping the cotton bud (c) writing the message (d) reading the message
16. 16.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
17. 17.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) it turned into air (d) the paper ate it
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) a mirror (d) a cotton bud
19. 19.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) a balloon (d) turmeric powder
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a small bowl (d) a balloon
21. 21.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) green (d) white
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a battery cell (c) a cotton bud (d) white paper
23. 23.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) plugging in the iron
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
25. 25.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
26. 26.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) reading the message
27. 27.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it can burn skin (d) it is cold
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) a cotton bud (c) lemon juice (d) a small bowl
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the ironing time
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
32. 32.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
33. 33.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
34. 34.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
35. 35.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) writing the message (d) dipping the cotton bud
36. 36.True or false: white paper is needed for the secret lemon message. (a) False (b) True
37. 37.True or false: putting the iron away is a job a child can do. (a) False (b) True
38. 38.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the juice scorches first (c) the iron is brown (d) heat adds colour
39. 39.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) an adult with an iron (c) white paper (d) lemon juice
40. 40.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True

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