Your parents are going to buy a house. They have been offered one on the roadside and another three lanes away from the roadside. Which house would you suggest your parents should buy? Explain your answer.
I would suggest my parents to buy the house which is three lanes away from the roadsides. It will protect us from the noise pollution. The house should bought away from roads in a peaceful place which gives positive energy and keeps you calm.
Sketch larynx and explain its function in your own words.
Explain in what way noise pollution is harmful to humans.
List sources of noise pollution in your surroundings.
Lightning and thunder take place in the sky at the same time and at the same distance from us. Lightning is seen earlier and thunder is heard later. Can you explain?
Fill in the blanks with suitable words.
(a) Time taken by an object to complete one oscillation is called ................... .
(b) Loudness is determined by the .........................of vibration.
(c) The unit of frequency is..........................
(d) Unwanted sound is called ......................... .
(e) Shrillness of a sound is determined by the ................. of vibration.
Which of the following voices is likely to have minimum frequency?
(a) Baby girl (b) Baby boy
(c) A man (d) A woman
Identify the part which vibrates to produce sound in the following instruments:
(a) Dholak (b) Sitar (c) Flute
A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.
What is the difference between noise and music? Can music become noise sometimes?
In the following statements, tick T against those which are true, and F against those which are false:
(a) Sound cannot travel in vacuum. (T/F)
(b) The number of oscillations per second of a vibrating object is called its time period. (T/F)
(c) If the amplitude of vibration is large, sound is feeble. (T/F)
(d) For human ears, the audible range is 20 Hz to 20,000 Hz. (T/F)
(e) The lower the frequency of vibration, the higher is the pitch. (T/F)
(f) Unwanted or unpleasant sound is termed as music. (T/F)
(g) Noise pollution may cause partial hearing impairment. (T/F)
Which of the following can be beaten into thin sheets?
(a) Zinc (b) Phosphorus (c) Sulphur (d) Oxygen
Fill in the blanks
(a) Most liquids that conduct electricity are solutions of , ______________ and ______________.
(b) The passage of an electric current through a solution causes ______________ effects.
(c) If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the terminal of the battery.
(d) The process of depositing a layer ofany desired metal on another material by means of electricity is called .
Give two examples each of situations in which you push or pull to change the state of motion of objects.
Fill in the blanks:
(a) Friction opposes the _____________ between the surfaces in contact with each other.
(b) Friction depends on the _____________ of surfaces. (c) Friction produces __________.
(d) Sprinkling of powder on the carrom board ________ friction.
(e) Sliding friction is ___________ than the static friction.
List conditions under which combustion can take place.
Indicate whether the following statements are True (T) or False (F).
(a) Unicellular organisms have one-celled body. (T/F)
(b) Muscle cells are branched. (T/F)
(c) The basic living unit of an organism is an organ. (T/F)
(d) Amoeba has irregular shape. (T/F)
Which of the following cannot be charged easily by friction?
(a) A plastic scale
(b) A copper rod
(c) An inflated balloon
(d) A woollen cloth.
Fill in the blanks:
(a) A place where animals are protected in their natural habitat is called .
(b) Species found only in a particular area is known as .
(c) Migratory birds fly to far away places because of changes.
Suppose you are in a dark room. Can you see objects in the room? Can you see objects outside the room. Explain.
What are the different ways in which water gets contaminated ?
Make a labelled diagram of a candle flame.
Make sketches of animal and plant cells. State three differences between them.
In an experiment 4.5 kg of a fuel was completely burnt. The heat produced was measured to be 180,000 kJ. Calculate the calorific value of the fuel.
What is a constellation? Name any two constellations.
What happens when
(a) Dilute sulphuric acid is poured on a copper plate?
(b) Iron nails are placed in copper sulphate solution?
Write word equations of the reactions involved.
What are antibiotics? What precautions must be taken while taking antibiotics?
Give reasons:
(a) Water is not used to control fires involving electrical equipment.
(b) LPG is a better domestic fuel than wood.
(c) Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not.
How are test tube babies born?
An inflated balloon was pressed against a wall after it has been rubbed with a piece of synthetic cloth. It was found that the balloon sticks to the wall. What force might be responsible for the attraction between the balloon and the wall?
What are the advantages of using CNG and LPG as fuels?