Materials required: Sugar, chalk powder, washing soda, sand, kerosene, lemon juice etc.
Procedure: Take six test tubes. Fill each one of them to half with water. Place them on a
test-tube stand. Add a pinch of sugar, chalk powder, washing soda and sand
each in separate test tubes. To the fifth test-tube, add 2–3 mL of kerosene, and
in the sixth test-tube, add 2–3 mL of lemon juice. Shake each test-tube well
and put them back on to the test-tube stand. Observe after 1-2 minutes. What
observe?
do you
Answers
Answer:
Wood Chair, table, plough, bullock cart and its wheels, …
Papier Books, notebooks, newspapers, toys, calendars, …
Leather Shoes, belt, purse, bag, jacket
Plastics Mug, bottle, bucket, toy
Cotton Clothes, curtains, bed sheets, sari
Properties of materials
Question 1.
List five each opaque and transparent materials.
Answer:
Opaque materials:
Wood
Iron
Cardboard
Brick
Gold.
Transparent materials:
Water
Glass
Air
Cellophine plastic, and
Fibre glass.
Question 2.
List five objects that are made from transparent materials.
Answer:
Beaker,
Test tube,
Conical flask,
Glass jug, and
Glass doors.
Question 3.
List five liquids that are transparent.
Answer:
Water
Hydrochloric acid
Alcohol
Acetone, and
Petrol.
Question 4
List five objects that are made from an opaque material.
Answer:
Books
Blackboard
Cardboard
Wall, and
Wooden furniture.
Question 5.
Why is water called universal solvent?
Answer:
The property of water to dissolve large number of materials makes it a universal solvent.
Question 6.
List three liquids which are miscible in water.
Answer:
Milk
glycerine, and
soft drinks.
Question 7.
List three liquids which are immiscible in water.
Answer:
Edible oil
kerosene oil, and
petrol.
Question 8.
State conditions when pure water can lose transparency.
Answer:
Water on cooling, freezes to form ice which is not transparent.
Question 9.
List the following substances as soluble and insoluble in water.
Sand, salt, sugar, paint, chilli powder, desi ghee, blotting paper.
Answer:
Water soluble substances: Salt, sugar.
Water insoluble substances: Sand, paint, chilli powder, desi ghee, blotting paper.
Question 10.
Show that sugar, common salt and washing soda are soluble while chalk powder, iodine and sand are insoluble in water.
Answer:
Take six test tubes, fill each of them about half with water. Keep each of them in a test tube stand. Add a pinch of each of six substances in separate test tubes. Shake well and allow to stand for few minutes. Common salt, sugar and washing soda dissolve while iodine, chalk powder and sand do not dissolve.
Question 11.
Describe a method to prove that water is a transparent material.
Answer:
Take a white sheet of paper, one sketch pen, one clean beaker and a small quantity of clean water. Now on white sheet mark a symbol (say “X’). Now put the empty beaker over the marked symbol. We can see it properly. Now put water in the beaker. Observe the same mark. The mark is again visible. This observation proves that water is transparent.
Question 12.
Why is a tumbler not made with a piece of cloth?
Answer:
This is because we generally use a tumbler to keep a liquid. A tumbler made of a piece of cloth cannot be used to keep water. So, a tumbler is made with a material which has a property to hold the liquid.
Question 13.
Explain with example rough and smooth surfaces.
Answer:
Rough surface: Materials which have uneven surface or ridges can be termed as a rough surface, e.g., coal.
Smooth surface: Materials which are plain and have an even surface are termed as a smooth surface, e.g., marble.
Appearance
Hardness
Solubility or insolubility
Float or buoyancy
Transparency.
Question 14.
Name two gases each which are soluble and insoluble in water. «
Answer:
Gases soluble in water are oxygen and carbon dioxide. Gases insoluble in water are hydrogen and nitrogen.
Question 15.
Write any four properties of materials.
Answer:
Four properties of materials are:
Appearance
Hardness
Solubility or insolubility
Float or buoyancy
Transparency.