List of top Science Questions

Would the bulb glow after completing the circuit shown in Fig. 9.14 if instead of safety pin we use an eraser?

Would the bulb glow after completing the circuit

Collect information about places where we get coal, petroleum and natural gas in India and mark the places in the outline map of India

Explain why the bulb would not glow in the arrangement shown in Fig. 9.13.

the bulb would not glow in the arrangement

Give two differences between a zygote and a foetus.
Match the items given in Column I with those in Column II:
Column I Column II
Chlorophyll Rhizobium
Nitrogen Heterotrophs
Cuscuta Pitcher plant
Animals Leaf
Insects Parasite
Fig shows the distance-time graph of three objects A, B and C. Study the graph and answer the following questions: 
distance-time graph of three objects
  1. Which of the three is travelling the fastest? 
  2. Are all three ever at the same point on the road? 
  3. How far has C travelled when B passes A? 
  4. How far has B travelled by the time it passes C?
Why do we apply paint on iron articles?
Describe with the help of a diagram an instrument which can be used to detect a charged body.
How do good animal husbandry practices benefit farmers?
In each of the following a force, F is acting on an object of mass, m. The direction of displacement is from west to east shown by the longer arrow. Observe the diagrams carefully and state whether the work done by the force is negative, positive or zero.
Observe work done by the force is negative, positive or zero
The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of the lens required to correct the problem?
Explain why sliding friction is less than static friction.
Find out the position of the image of an object situated at A in the plane mirror

(a) Find out the position of the image of an object situated at A in the plane mirror.
(b) Can Paheli at B see this image?
(c) Can Boojho at C see this image?
(d) When Paheli moves from B to C, where does the image of A move?
Draw the structure of a neuron and explain its function.
In the following statements, tick ‘T’ against those which are true, and ‘F’ against those which are false.
  1. Sound cannot travel in vacuum. (T/F)
  2. The number of oscillations per second of a vibrating object is called its time period. (T/F)
  3. If the amplitude of vibration is large, sound is feeble. (T/F)
  4. For human ears, the audible range is 20 Hz to 20,000 Hz. (T/F)
  5. The lower the frequency of vibration, the higher is the pitch. (T/F)
  6. Unwanted or unpleasant sound is termed as music. (T/F)
  7. Noise pollution may cause partial hearing impairment. (T/F)
Explain the following terms with one example each. 
(a) Corrosion 
(b) Rancidity
A stone of 1 kg is thrown with a velocity of 20 m s–1 across the frozen surface of a lake and comes to rest after traveling a distance of 50 m. What is the force of friction between the stone and the ice?

Draw:

1) a leaf

2) a taproot and

3) a flower,

you have studied for Table 4.3

The speed-time graph for a car is shown is Fig.
The speed-time graph for a car
 
  1. Find how far does the car travel in the first 4 seconds. Shade the area on the graph that represents the distance travelled by the car during the period. 
  2. Which part of the graph represents uniform motion of the car?
A battery of 9 V is connected in series with resistors of 0.2 Ω, 0.3 Ω, 0.4 Ω , 0.5 Ω and 12 Ω, respectively. How much current would flow through the 12 Ω resistor?
Find the energy in joules consumed in 10 hours by four devices of power 500 W each.
Explain why a charged body loses its charge if we touch it with our hand.
A hockey ball of mass 200 g traveling at 10 m s–1 is struck by a hockey stick so as to return it along its original path with a velocity at 5 m s–1. Calculate the magnitude of the change of momentum that occurred in the motion of the hockey ball by the force applied by the hockey stick.

The bulb in the circuit shown in Fig. does not glow. Can you identify the problem? Make necessary changes in the circuit to make the bulb glow.

The bulb in the circuit

Balance the following chemical equations.
(a) HNO3 +Ca(OH)2 \(→\) Ca(NO3)2 + H2O 
(b) NaOH + H2SO4 \(→\) Na2SO4 + H2O 
(c) NaCl + AgNO3 \(→\) AgCl + NaNO3 
(d) BaCl + H2 SO4 \(→\) BaSO4 + HCl