Science M.C.Q. [I MARKS]

Shyam was cooking potato curry on a chulha. To his surprise, he observed that the copper vessel was getting blackened from outside. It may

Which one among the following is considered as the cleanest fuel?

On placing an inverted tumbler over a burning candle, the flame extinguishes after some time. This is because of non-availability of

If a person's clothes catch fire, the best way to extinguish the fire is to

The substance that does not burn with flame is

When a lighted candle placed partly in a trough of water is covered by an inverted glass, water rushes up as shown and the flame extinguishes. If the above hypothesis is true, what will happen after the candle blows out in the new experimental set-up.

Bunsen burner contains a gas X which burns with a blue flame. What is the reason behind the blue coloured flame ?

Our beautiful Taj Mahal is suffering from 'marble cancer'. Acid rain reacts with marble and limestone to form calcium sulphate. It causes damage to big sculptures and marble constructions.
Identify the gases that contribute to the formation of acid rain.

Assertion (A) Candle can burn a block of wood.
Reason (R) Ignition temperature of wood is high.

Assertion (A) Electrical components can catch fire.
Reason (R) Electrical fire can be extinguished using water.

Which of the following fire extinguishers is suitable for tackling electrical fires ?

What is the minimum temperature at which a substance catches fire and burns on it's own ?

Which type of combustion is characterised by a lack of oxygen during the burning process ?

Assertion (A) When a burning candle is covered with a glass jar, the flame goes out.
Reason (R) The glass jar prevents the flow of oxygen to the candle flame.

Assertion (A) LPG gas can catch fire easily.
Reason (R) LPG have high ignition temperature.

Assertion (A) Spontaneous combustion can occur in materials like dry leaves.
Reason (R) Spontaneous combustion happens due to the presence of excess oxygen in materials.

Assertion (A) Fireworks produce different colours.
Reason (R) Different chemicals are used in the fireworks to produce different colours.

Which one of the following has the highest calorific value ?

In villages, people use wood as fuel because

The calorific value of a fuel is expressed in a unit called

What is the main product of incomplete combustion of coal ?

Which is the hottest zone in a candle flame ?

Unburnt carbon particles are present in the

Which of the following case is an example of spontaneous combustion ?

In a fire extinguisher, which substance is commonly used for cutting off the oxygen supply to the fire ?

Water was poured over a large oil fire to extinguish it. What would happen and why ?

The substance expected to have the highest ignition temperature out of the following is

A substance which reacts with oxygen giving heat is called a combustible substance. Which one of the following is a combustible substance ?

Which of the following is not a combustible substance ?

Which of these materials is combustible ?

Coal burns with

Magnesium ribbon on burning in air produces

The product(s) of combustion is/are

Combustion is generally

Combustion is a process that