1. Solution:
(b): Soft drink
Soft drinks contain water, carbon dioxide and acid due to which iron nail is corroded and appears dull.
2. Solution:
(c): Glucose
Glucose is one substance which is completely soluble in water.
3. Solution:
(c): Magnifying glass and glass tumbler
Magnifying glass and glass tumbler are transparent materials.
4. Solution:
Solution:
(c): Mirror and Magnet
A mirror is opaque since it is painted on one side.
Magnet is opaque since it is made up of iron metal.
5. (c): Muslin cloth
Muslin cloth is translucent since we can see through it but not clearly.
Glass tumbler is transparent.
Mirror and aluminum foil are opaque.
6. (b): Feather, plastic ball
Feather and plastic ball will float on water since they are lighter than water.
7. (d): Steel and plastic
Steel can be moulded to get sharp points and plastic is used to seal the edges. Hence steel and plastic are used for making safety pins.
8. Solution:
(c): Wood
Wood is not lustrous since it is not a crystalline substance.
9. Solution:
(c): Materials are grouped for fun.
Materials are usually grouped to study their properties and according to their uses in systematic manner. Hence materials are not grouped for fun.
10. Solution:
(d): Eraser
Eraser is made up of rubber while tawa, pressure cooker and spade are made up of metal.
11. Solution:
(a): Transparent
Transparent glass is used for making the front glass of a car so that everything can be seen clearly.
12. Solution:
Paheli could see the difference in the appearance of two metals since silver reacts with some gases like hydrogen sulphide and loses its shine in moist air. Gold is a noble metal which does not react with the gases present in the atmosphere.
13. Solution:
Raveena will get the mixture in solution form. Since honey and water are soluble with each other hence a solution will be formed when honey is mixed with water.
14. Solution:
Yes, Shikha’s brother could locate her since the glass door which she hid is transparent in nature.
15. Solution:
Initially, the cotton ball floats on water since it is lighter. Slowly it absorbs water and becomes heavy and later sinks in water.
16. Solution:
Leaf, rubber band, cooked rice, eraser and fresh chapati are soft materials because they can be scratched or compressed easily.
17. Solution:
Soluble pairs
(i) Honey – water
(ii) Mustard oil – groundnut oil
(iii) Glucose – water
Insoluble pairs
(i) Mustard oil – water
(ii) Turmeric – water
(iii) Rice flour – water
18. Solution:
| Name of the material | Appearance (Hard/Soft) | Transparency (Transparent/Translucent/Opaque) | Floats/Sinks in water | Soluble/Insoluble in water |
| Lump of salt | Hard | Opaque | Sinks | Soluble |
| Green grass | Soft | Opaque | Floats | Insoluble |
| Broken glass piece | Hard | Transparent | Sinks | Insoluble |
| Thermocol box | Soft | Opaque | Floats | Insoluble |
| Pen | Hard | Opaque | Floats | Insoluble |
| Iron nail | Hard | Opaque | Sinks | Insoluble |
| Glass marbles | Hard | Transparent | Sinks | Insoluble |
| Hair | Hard | Opaque | Floats | Insoluble |
| Naphthalene ball | Hard | Opaque | Floats | Insoluble |
| A piece of sugar candy | Hard | Opaque | Sinks | Soluble |
19. Solution:
The arranged word are:
(a) Aluminium – It can be used to wrap food in the foil, in making aircraft, etc.
(b) Plastic – It can be used as buckets/pencil box, etc.
(c) Kerosene – It can be used as fuel, solvent, etc.
(d) Vinegar – It can be used as a preservative, food ingredients, etc.
20. Solution:
The correct match is:
| Column I | Column II |
| (a) Surgical instruments | (iii) Steel |
| (b) Newspaper | (iv) Plant product |
| (c) Electrical switches | (i) Plastic |
| (d) Wool | (ii) Animal product |
Objects that are opaque and would sink in water are:
(i) Coin
(ii) Stone
(iii) Key
(iv) Pencil
(v) Eraser
22. Solution:
Few properties by which we can prove that these materials are different:
Chalk – Hard, rough, non-lustrous
Iron nail – Hard, smooth, lustrous
Wood – Hard, rough, non-lustrous
Aluminium – Hard, smooth, lustrous
Candle – Hard, smooth, non-lustrous
Cotton – Soft, smooth, non-lustrous
23. Solution:
Aquatic animals and plants use oxygen which is dissolved in water for breathing and photosynthesis.
24. Solution:
Those substances through which objects cannot be seen are termed as opaque substances. Example: wood, stone.
Those substances through which objects can be seen but not clearly are termed as translucent substances. Example: frosted glass, oiled paper.
Those substances through which objects can be seen clearly are termed as transparent substances. Example: crystal clear water, glass.
25. Solution:
Soluble in water:
Sugar
Salt
Honey
Copper sulphate crystals
Glucose
Insoluble in water:
Mustard oil
Sand
Sawdust
Chalk powder
Petals of flower
Soil
Wheat flour
