1.The appearance of potash-lime glass in colour is:
a) Black
b) Green to colourless
c) Reddish brown
d) White
Explanation: The potash-lime glass has a greenish colour as a result of high iron content in the sand used to make the glass.
2. Natural rubber contains polymers of an organic compound:
a) Polyprene
b) Neoprene
c) Thiokol
d) Isoprene
Explanation: Rubber primarily consists of Isoprene. It may contain certain impurities like organic compounds and water.
3. Rubber is extremely water-proof.
a) True
b) False
Explanation:Rubber consists of mainly hydrocarbons. It also contains resins, fatty acids and sterols. These provide water proofing quality to rubber.
4.What is added to rubber to make it a thermosetting polymer?
a) Potassium
b) Sulphur
c) Sodium
d) Phosphorous
Explanation: The process of vulcanization makes rubber get converted into a heavily cross-linked, insoluble and infusible compound. It is done by adding sulphur and litharge (PbO).
5. Rubber latex is used for:
a) Bonding wood plys
b) Bonding rubber to walls
c) Bonding rubber to wood
d) Bonding tools
Explanation: It is a solution of rubber hydrochloride. It has a sticky texture and has excellent adhesive property.
6. Rubber seed oil can be used in:
a) Paint
b) Medicine
c) Varnish
d) Fuel
Explanation: It can be used as a semi-drying oil in paints. It partially hardens when exposed to air unlike other drying oils in the paint.
7. Recycled crumb rubber can be used in:
a) Plastering
b) Mortar
c) Paints
d) Concrete
Explanation: Good compressive strength results were obtained when 25% of sand was replaced by rubber. It is economical and conserves sand usage
8.What is resilience?
a) Strength
b) Elasticity
c) Soundness
d) Durability
Explanation: When rubber is subjected to a load, it deforms. On removal of the load, it returns back to its original shape and size. This property is resilience.
9. Rubber bricks are generally used for:
a) Roofing
b) Walls
c) Floorings
d) Lining pizza ovens
Explanation: Rubber bricks are manufactured from recycles tyres. They are resistant to water and don’t become slippery when wet. They are extensively used as flooring in toilets, pavements and horse stables.
10. Hardness of rubber is measured on which scale?
a) Rockwell scale
b) Shore scale
c) Mohr’s scale
d) Vicker’s scale
Explanation: Hardness is measured in terms of durometer on a shore scale. Shore A is used for soft to medium-hard rubber. Solid rubber has a hardness of 40 duro.