Available Answers

1. 1.

   Choose and write the correct answer(MCQs):

   1. Streamlined shape help to reduce:
      1. air friction
      2. water friction
      3. air and water friction 
      4. none of these
   2. Friction can be increased by:
      1. polishing
      2. using lubricants
      3. making surface rough
      4. using ball bearing
   3. The lower end of the rod of the lightning conductor is connected to the:
      1. electric pole
      2. earth plate
      3. copper plate
      4. building
   4. Which of the following cannot be charged easily by friction:
      1. a copper rod
      2. a ball of wood
      3. a floated ballon
      4. a glass rod
   5. The magnitude of tremors is taken as mild if they measure or less:
      1. 1
      2. 3
      3. 2
      4. 5
   6. The point of origion of earthquake is called:
      1. hypocentre
      2. mid-centre
      3. epicentre
      4. hypercentre
   7. The liquid, which conducts electricity and undergoes decomposition is called:
      1. electrolytes 
      2. electrode
      3. electrolysis
      4. electromagnet
2. 2.

   Fill in the blanks:

   1. Pitch depends on ___________ of the sound.
   2. Time taken to complete one oscillation is the ____________.
   3. Lightning ___________ protects high buildings from the damage cause by lightning.
   4. ____________ is the surest test of electrification.
   5. When two mirrors are set at an angle to each other then many___________.
   6. The rainbow is seen as a large ____________ in the sky with many colours.
   7. People use fuels like __________, ___________ and ____________ to cook food.
3. 3.

   Write T for true or F for false:

   1. Every all has a cytoplasm.
   2. Nucellus has a distinct limiting membrane.
   3. All pushes and pulls are forces.
   4. Friction causes wastage pf energy.
   5. By using the dry surface, friction can be reduced.
   6. The spikes on shows of athletes reduces the friction.
   7. One hertz one vibration per second.
   8. Excessive noise can cause deafness.
4. 4.

   Match the column A with column B:

   A	B
   1. A planet closest to the sun	a. Galaxy
   2. A planet farthest from the sun	b. Mars
   3. A cluster of billions of stars	c. Neptune
   4. Prominent ring system	d. Mercury
   5. Ursa major	e. Saturn
   6. A reddish coloured planet	f. The Big Dipper

    

5. 5.

   Describe the role of lubricants of soap solution in reducing friction.
6. 6.

   Give the disadvantages of friction.