Available Answers

1. 1.

   Write/Choose the correct answer.

   1. Oxygen is collected in the jar by downward displacement of water. (True/False)
   2. Oxygen does not support combustion. (True/False)
   3. _______ is the reddish-brown hydrated iron oxide which depends on iron objects when exposed to most air.
   4. _______ is the process of deposition a thin layer of zinc metal on iron objects.
   5. During the process of photosynthesis, carbon dioxide is released into the atmosphere and oxygen present in the atmosphere is used by the plants. (True/false)
   6. Metallic oxides are _______ in nature.
   7. The amount of oxygen in the air remains constant. (True/False)
2. 2.

   Fill in the blanks.

   1. _______ is an essential component of proteins and amino acids.
   2. Nitrogen is neutral to _________.
   3. The process of conversion of free atmosphere nitrogen into usable compounds is called __________.
   4. When nitrogen reacts with rainwater, it forms _________.
   5. _______ present in the soil convert the nitrates present in the animal waste into atmospheric nitrogen.
3. 3.

   Write/Choose the correct answer.

   1. During laboratory preparation, carbon dioxide gas is envolved with brisk effervescence. (True/False)
   2. Carbon dioxide is ______ times heavier than air.
   3. When a moist blue litmus paper is introduced in a gas jar full of carbon dioxide, the litmus paper turns______.
   4. Carbon dioxide is released when _____ is used in the manufacture of bakery items.
4. 4.

   Write true (T) false (F).

   1. Water vapour present in the air are known as humidity.
   2. Water vapour affect the rate of transpiration in plants.
   3. Water vapour do not influence the water cycle.
   4. Fog often reduces the visibility similar to a cloud but at a lower level.
   5. Snow is a mass of fine water droplets in the atmosphere near or in contact with the earth.
5. 5.

   Match the following.

   Column A	Column B
   1. Weather observation balloons	a. Xenon
   2. Tubes designed for advertising purposes and street lighting	b. Radon
   3. Welding metals	c. Helium
   4. High intensity electric lamps	d. Argon
   5. Treatment of cancer	e. Neon

    

6. 6.

   Fill in the blanks.

   1. Any substance which pollutes the air is called _______.
   2. Carbon monoxide on combining with haemoglobin forms ______.
   3. _____ is a mixture of smoke and fog.
   4. ______ of fuels like coal, petrol and diesel may heavy like lead, copper and cadmium in the air.
   5. ________ are used in refrigeration, air conditioners ans aerosol cans.