CBSE Class 7 Science Advanced Chemistry Chemistry in Daily Life Very Short Answer Questions Set 03

Very Short Answer Questions

Question 1. State whether true or false: Blue vitriol is used as a fungicide for grape plants.
Answer:
True
Blue vitriol is used as a fungicide for fruit trees in the form of Bordeaux mixture.
In simple words: Copper sulphate protects grape vines from insects and fungus.

Teacher's Note:
1. Bordeaux mixture contains copper sulphate and lime.
2. Blue vitriol is hydrated copper sulphate.

Question 2. State whether true or false: Deficiency of potassium iodide causes goitre in humans.
Answer:
False
Deficiency of iodine causes goitre in human beings (the iodide salts are only the source of iodine).
In simple words: Goitre is due to a lack of iodine, which is why iodized salt is used.

Teacher's Note:
1. The accepted answer links goitre to iodine deficiency.
2. Iodized salt is the remedy.

Question 3. State whether true or false: Carbohydrates are the compounds of carbon, hydrogen and oxygen.
Answer:
True
Carbohydrates generally contain carbon, hydrogen and oxygen.
In simple words: Carbohydrates are made of C, H and O.

Teacher's Note:
1. Proteins also contain nitrogen.
2. Glucose is one example.

Question 4. State whether true or false: Water glass is used for making the lenses of telescopes.
Answer:
False
Optical glass is used for making telescope lenses. Water glass is sodium silicate.
In simple words: Lenses are made of optical glass, not water glass.

Teacher's Note:
1. Water glass is soluble in water.
2. It is used in the soap industry.

Question 5. State whether true or false: Plastics are polymers.
Answer:
True
Plastics are made of polymers: long chains of repeating units.
In simple words: Plastics are polymers.

Teacher's Note:
1. The small repeating unit is the monomer.
2. Polyethylene is an example.

Question 6. Fill in the blank: _______ is an example of medicine extracted from the bark of a plant.
Answer:
Quinine
In simple words: Quinine comes from the bark of the cinchona plant.

Teacher's Note:
1. It is used against malaria.
2. Medicines were first got from plants.

Question 7. Fill in the blank: Duralumin contains _______ % of aluminium.
Answer:
95
In simple words: Duralumin has 95% aluminium.

Teacher's Note:
1. The rest is copper, manganese and magnesium.
2. It is light and strong.

Question 8. Fill in the blank: Noble gases are chemically _______.
Answer:
Inert
In simple words: Noble gases do not react easily.

Teacher's Note:
1. Inert means non-reactive.
2. That is why they are used in bulbs and balloons.

Question 9. Fill in the blank: _______ are generally non-malleable and non-ductile.
Answer:
Non-metals
In simple words: Non-metals cannot be hammered or drawn into wires.

Teacher's Note:
1. They are brittle.
2. Metals are malleable and ductile.

Question 10. Fill in the blank: _______ is the least reactive metal which is used as a catalyst.
Answer:
Platinum
In simple words: Platinum is the least reactive metal used as a catalyst.

Teacher's Note:
1. It is a precious metal.
2. It speeds up gas reactions.

Question 11. Fill in the blank: Xenon and krypton are used in electric bulbs to slow down the _______ of tungsten.
Answer:
Sublimation
In simple words: They slow the sublimation of the hot filament.

Teacher's Note:
1. Sublimation is solid turning directly into vapour.
2. Slower sublimation means longer bulb life.

Question 12. Fill in the blank: _______ are the organic compounds containing carbon, hydrogen, oxygen and nitrogen.
Answer:
Proteins
In simple words: Proteins contain C, H, O and N (and sometimes S and P).

Teacher's Note:
1. Proteins build and repair cells.
2. Carbohydrates and fats have no nitrogen.

Question 13. Fill in the blank: Graphite is a _______ conductor of heat.
Answer:
Bad (poor)
In simple words: Graphite does not conduct heat well, though it conducts electricity.

Teacher's Note:
1. It resists heat.
2. It conducts electricity.

Question 14. Fill in the blank: _______ glass is used as wind shields of automobiles.
Answer:
Shatterproof (sandwich)
In simple words: Two glass sheets with a plastic sheet between them do not scatter when broken.

Teacher's Note:
1. Sandwich glass is another name.
2. The plastic layer holds the pieces.

Question 15. Fill in the blank: _______ is used as fuse wire in thermite welding.
Answer:
Magnesium
In simple words: Magnesium wire (ribbon) is used as the fuse to start thermite welding.

Teacher's Note:
1. It burns with a dazzling flame.
2. It also goes into fireworks.

Teacher's Note:
1. Use the metals and non-metals tables.
2. More than one answer is possible.

Teacher's Note:
1. The alloys table shows brass for ammunition shells.
2. Bronze is used for statues, coins and utensils.

Teacher's Note:
1. Mortar joins bricks and plasters.
2. Pure cement is used in grouting.