C & F + Synthetic Fiber

Which of the following statement is not correct about carbon dioxide acting as a fire extinguisher for

electrical fires ?

• it is heavier than air

• it is lighter than air

• it is not combustible

• it does not support combustion

Which of the following does not involve a combustion reaction ?

• (a) production of heat and light from kerosene in a lantern

• (b) production of heat and light from hydrogen in a rocket

• (c) production of heat and light from hydrogen in the sun

• (d) production of heat and light from wood in a bonfire

A heap of green leaves is lying in one corner of a park. The green leaves in the heap burn with difficulty

because :

• a) they contain a tough material called cellulose

• b) they contain a lot of water

• c) they contain a green pigment chlorophyll

• d) they do not get sufficient oxygen for burning

Which of the following is not used in making matchsticks these days ?

• (a) potassium chlorate

• (b) white phosphorus

• (c) antimony tri sulphide

• (d) red phosphorus

On a cold winter night, the persons sleeping in a room with closed door and windows with a coal fire

burning inside may die due to the excessive accumulation of :

• (a) nitrogen monoxide

• (b) nitrogen dioxide

• (c) carbon dioxide

• (d) carbon monoxide

Abida and Ramesh want to heat water taken in separate beakers. Abida kept the beaker near the wick in

the yellow part of the candle flame. Ramesh kept the beaker in the outermost part of the flame. Whose

water will get heated in a shorter time ?

• Abida

• Ramesh

• Both will take same time

• can not be determined

Choose the correct option:

• A (non luminous , coolest)

• B(luminous, moderately hot)

• C (dark zone, hottest)

• A (luminous, hottest

Calculate the CV if 6kg of fuel is burnt to produce 90000 kJ of heat

• 15000kJ/kg

• 15000J/kg

• 1500 kJ/g

• 150 kJ/kg

The condition which are not necessary for combustion to take place.

• Presence of air

• Presence of combustible substance

• Heating till ignition temperature

• Presence of CO₂ and H₂O

fire produced by oil spill can not be extinguished by :

• removing the fuel

• by pouring water

• By cutting off the air supply to the burning substances

• by soda acid fire extinguisher