Science [3 Marks Each] QUE-ANS

Substances which are soluble:

• Honey in water.
• Glucose in water.

Groundnut oil in mustard oil substances which are insoluble:

• Turmeric in water.
• Rice flour in water.
• Mustard oil in water.

Four properties of materials are:

1. Appearance.
2. Hardness.
3. Solubility or insolubility.
4. Float or buoyancy.
5. Transparency.

1. Books.
2. Blackboard.
3. Cardboard.
4. Wall.
5. Wooden furniture.

The substances which dissolves in water are called soluble substances. For example: Salt, sugar, milk, etc. The substances which do not dissolve in water are called insoluble substances. For example: Chalk powder, sand, stone, etc. The property of substance due to which it dissolves in water is called solubility.

The grouping of various objects can be done on the basis of following characters:

• Size.
• Shape.
• Colour.
• Hardness.
• Solubility in water.
• Attraction towards magnet.
• Conduction of heat.
• Transparency, etc.

Classification is essential for:

1. Identification of objects.
2. Sorting of objects.
3. Lozating things.
4. Understanding similarities and dissimilarities among objects.
5. Making the study of objects easy and more meaningful.

Oxygen gas dissolves in water i.e. oxygen gas is soluble in water. The plants and animals which live in water use the oxygen dissolved in water for respiration. Thus, oxygen gas dissolved in water is very important for the survival of animals and plants that live in water.

Arrangement of the words and their uses are as follows:

1. Aluminium It is used in foil, aircrafts, etc.
2. Plastic It is used in making bucket, pencil box, etc.
3. Kerosene It is used as a fuel, solvent, etc.
4. Vinegar It is used in food ingredient, preservative, etc

Gold metal does not lose its shine or luster when exposed to atmosphere. So gold ornaments look new even after several years of use. Actually, gold metal is highly unreactive metal which remains unaffected by air, water and other gases in the atmosphere whereas silver metal on long exposure to moist air loses its shine and becomes dull. That why old silver spoon was giving dull appearance.

Materials which can be compressed, cut, bent (moulded) or scratched easily are called soft materials.Rubber band, leaf, eraser, cooked rice and fresh chapati are soft materials because they can be compressed, cut, bent or scratched easily.

1. Beaker.
2. Test tube.
3. Conical flask.
4. Glass jug.
5. Glass doors.

Substances which completely dissolve in water are soluble in water. Substances soluble in water are sugar, salt, honey, copper sulphate crystals, glucose. Substances which does not dissolve in water are insoluble in water. Substances insoluble in water are mustard oil, sand, sawdust, chalk powder, petals of flower, soil, wheat flour.

Name of the objects, which are opaque and would sink in water are:

1. Coal
2. Stone
3. Pencil
4. Eraser
5. Coin

Opaque Those materials through which we cannot see at all are called opaque materials, e.g. Car board. Translucent Those materials through which we cannot see clearly are called translucent materials, e.g. Butter paper. Transparent Those materials through which we can see clearly are called transparent materials e.g. Glass.

Yes, her brother can easily locate her because glass door is a transparent material. The transparent materials allow almost all the light to pass through them due to which the object or person behind them can be seen clearly.

Transparent: Glass, water.
Translucent: Oily paper.
Opaque: Cardboard, wood, stone, metal.

We can differentiate these materials on the basis of lustre, hardness, softness, roughness or smoothness.

Material	Properties
Chalk	Rough on the surface, cannot be compressed.
Iron nail	Shine (lustre), hard
Aluminium	Shine (lustre), hard
Wood	Shine (lustre), hard
Candle	Soft to compress
Cotton	Soft to compress

1. Water.
2. Hydrochloric.
3. Alcohol.
4. Acetone.
5. Petrol.

• Shoes: Leather, rubber, plastic, canvas
• Chair: Wood, metal, plastic, concrete
• Coins: Copper, silver, gold
• Utensils: Iron, copper, aluminium
• Clothes: Cotton, wool, silk, rayon, nylon.