Water is not effective on petrol fire because it has higher density than petrol as a result of which it sinks to the bottom, while petrol stays afloat and keeps burning. Petro-chemical fires are nearly always extinguished with chemical foam.

Correct Option: D

Water is not effective on petrol fire because it has higher density than petrol as a result of which it sinks to the bottom, while petrol stays afloat and keeps burning. Petro-chemical fires are nearly always extinguished with chemical foam.

Pure and simple, asbestos is a group of naturally occurring minerals. It is composed of calcium and magnesium silicate. Asbestos occurs as veins in rocks and is mined from the ground, similar to coal.

Correct Option: A

Pure and simple, asbestos is a group of naturally occurring minerals. It is composed of calcium and magnesium silicate. Asbestos occurs as veins in rocks and is mined from the ground, similar to coal.

Helium is used since it has very low (almost nonexistent) narcotic properties. The nitrogen in air is highly narcotic at depth and adding helium allows one to dive without the effects of narcosis (where one's mind is impaired).

Correct Option: D

Helium is used since it has very low (almost nonexistent) narcotic properties. The nitrogen in air is highly narcotic at depth and adding helium allows one to dive without the effects of narcosis (where one's mind is impaired).

Heavy metals (cadmium, cobalt, chromium, copper, mercury, manganese, nickel, lead, zinc, molybdenum, tin) are among the main pollutants. Industrial paints are loaded with metals such as lead, calcium, cadmium and other such chemicals. When any amount of paint is led off into the water bodies it causes water pollution by causing the amount of heavy metals present in water to fluctuate. Each one of these has severe toxic effects on living beings, and tend to accumulate in aquatic food chains.

Correct Option: A

Heavy metals (cadmium, cobalt, chromium, copper, mercury, manganese, nickel, lead, zinc, molybdenum, tin) are among the main pollutants. Industrial paints are loaded with metals such as lead, calcium, cadmium and other such chemicals. When any amount of paint is led off into the water bodies it causes water pollution by causing the amount of heavy metals present in water to fluctuate. Each one of these has severe toxic effects on living beings, and tend to accumulate in aquatic food chains.

Lime water is calcium hydroxide (Ca(OH)₂ ). When carbon dioxide is passed into it, it turns milky because of the formation of calcium carbonate: Ca(OH)₂ + CO₂ ® CaCO₃ + H₂O

Correct Option: A

Lime water is calcium hydroxide (Ca(OH)₂ ). When carbon dioxide is passed into it, it turns milky because of the formation of calcium carbonate: Ca(OH)₂ + CO₂ ® CaCO₃ + H₂O