What is the role of ultraviolet (UV) radiation in the water purification system?
1. It inactivates / kills the harmful micro- organisms in water.
2. It removes all the undesirable odours from the water.
3. It quickens the sedimentation of solid particles and improves the clarity of water.
Which of the statements given above is/are correct?
Biogas mainly consists of
Which one of the following sets of elements was primarily responsible for the origin of life on the Earth?
What is “ Kiss of death” ?
Domestic cooking gas consists of mostly
The inexhaustible source of energy of the stars is due to
Which one of the following pairs is correctly matched?
Acid rains is caused due to emission of which of the following into the atmosphere?
Consider the following statements:
If there were no phenomenon of capillarity
1. It would be difficult to use a kerosene lamp.
2. One would not be able to use a straw to consume a soft drink.
3. the blotting paper would fail to function.
4. the big trees that we see around would not have grown on the earth.
Which of the statements given above are correct?
H2O is liquid and H2S is a gas because
While tinning of brass utensils, the ammonium chloride powder used to clean the hot utensil produces fumes of
The blue colour of water in the sea. What is the reason behind the phenomenon?
Hydrogen bomb is based on the principle of
Consider the following statements: Hard water is not suitable for
1. Drinking
2. Washing clothes with soap
3. Use in boilers
4. Irrigating crops
Which of these statements are correct?
When soggy biscuits are kept inside the fridge for sometime they become crisp because
Consider the following statements and select the correct code.
Assertion (A): A chemical reaction becomes faster at higher temperature.
Reason (R): At higher temperature, molecular motion becomes more rapid.
Living in the atmosphere of CO is dangerous because it
The order of appearance of the following with increasing temperature during the refining of crude oil is
The difference between a nuclear reactor and atomic bomb is that
Consider the following parts of spectra:
1. Visible 2. Infrared 3. Ultraviolet 4. Microwave
Which of the following is the correct sequence in which the wavelengths increase?
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-
-
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Which one of the following is not correct?
Which one of the following statements is not true about cosmic rays?
Helium is preferred to hydrogen in air balloons because it
Which of the following substances is/are ozone depleting?
Select the correct answer from the codes given below:
1. Chlorofluorocarbons
2. Halons
3. Carbon tetrachloride