Science questions in on sentence. [1 M]

Name the unit in which the calorific value of a fuel is expressed.

Abida and Ramesh were doing an experiment in which water was to be heated in a beaker. 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?

Which zone of a flame does a goldsmith use for melting gold and silver and why?

What is fuel?

Write True and False against the following statements and also correct the false statement. A physical process in which a substance reacts with oxygen to give off heat is called combustion.

Some words (underlined) in the following sentences are jumbled up. Write them in their correct form.Chittsmack does not burn by itself.

Which zone of a candle flame is the hottest?

What is meant by explosive combustion (or explosion)? Give one example of explosive combustion (or explosion).

Fill in the blanks in the following sentences:The substances which have very ________________ ignition temperature and can easily catch fire with a flame are called __________ substances.

Indicate whether the following statements are True or False. Also write the false statements in their correct form.Air is necessary for combustion.

Write True and False against the following statements and also correct the false statement. Greater the calorific value, better is the fuel.

Name the term which is used to express the efficiency of a fuel.

Name two substances having low ignition temperatures and two having high ignition temperatures.

Write True and False against the following statements and also correct the false statement.The substances which vapourise during burning, give flame.

Name the fuel which is gradually replacing petrol and diesel in automobiles.

What are non-combustible substances? Name three non-combustible substances.

Fill in the blanks. A liquid fuel, used in homes is .

Indicate whether the following statements are True or False. Also write the false statements in their correct form.Magnesium is a non-combustible metal.

Which is the best fire extinguisher for fires involving electrical equipment and inflammable materials like petrol?

If you hold a piece of iron wire with a pair of tongs inside a candle flame or a Bunsen burner flame, what will you observe? Will it produce a flame?

Name the very poisonous gas produced by the incomplete combustion of fuels.

Name one solid, one liquid and one gas which burn by producing a flame.

In which zone of a candle flame: Complete combustion of fuel takes place?

Some words (underlined) in the following sentences are jumbled up. Write them in their correct form.Seldie is a combustible substance.

Write True and False against the following statements and also correct the false statement.Middle zone is the hottest zone of a flame.

What are combustible substances? Name three combustible substances.

Which of the two has a lower ignition temperature: petrol or kerosene?

Fill in the blanks in the following sentences: The __________ temperature at which a substance catches fire is called its __________ temperature.

Write True and False against the following statements and also correct the false statement.Increased concentration of nitrogen in air is believed to cause global warming.

Some words (underlined) in the following sentences are jumbled up. Write them in their correct form.Some substances on combustion produce thea and mafel.

Fill in the blanks.
Fuel must be heated to its before it starts burning.

Fill in the blanks in the following sentences:The substances which vapourise during _______ give flame.

Fill in the blanks. Burning of wood and coal causes of air.

Write True and False against the following statements and also correct the false statement.Water is the best extinguisher for fires involving electrical equipment.

Name one substance which undergoes spontaneous combustion (or burns in air at room temperature).

What is meant by rapid combustion? Give one example of rapid combustion.

Some words (underlined) in the following sentences are jumbled up. Write them in their correct form.Slags is a non-combustible material.

What is meant by spontaneous combustion? Give one example of spontaneous combustion.

Explain why, fire caused by electricity should not be extinguished by pouring water.

Name one fuel which burns without producing a flame.

Write the unit of calorific value.

An electric spark is struck between two electrodes placed near each other in a closed tank full of petrol. Will the petrol catch fire? Explain your answer.

Give reasons. Water is not used to control fires involving electrical equipment.

Fill in the blanks. Fire produced by oil cannot be controlled by .