Describe with the help of a diagram an instrument which can be used to detect a charged body.
An electroscope can be used to detect whether a body is charged or not. In an electroscope, two metal foils are hanged with the help of a conductor in the glass jar with lid. When a charged body touches this conductor then its charges get transferred to the metal foil and they separates due to like charges. This shows that an electroscope detect charges.
Explain why a charged body loses its charge if we touch it with our hand.
Suppose you are outside your home and an earthquake strikes. What precaution would you take to protect yourself?
Explain why a charged balloon is repelled by another charged balloon whereas an uncharged balloon is attracted by another charged balloon?
Sometime, a crackling sound is heard while taking off sweater during winters. Explain.
Suggest three measures to protect ourselves from lightning.
Name the scale on which the destructive energy of an earthquake is measured. An earthquake measures 3 on this scale. Would it be recorded by a seismograph? Is it likely to cause much damage?
List three states in India where earthquakes are more likely to strike.
When a glass rod is rubbed with a piece of silk cloth the rod
(a) and the cloth both acquire positive charge.
(b) becomes positively charged while the cloth has a negative charge.
(c) and the cloth both acquire negative charge.
(d) becomes negatively charged while the cloth has a positive charge.
The weather department has predicted that a thunderstorm is likely to occur on a certain day. Suppose you have to go out on that day. Would you carry an umbrella? Explain.
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.
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)
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 ?
Explain the importance of reproduction in organisms.
Some properties are listed in the following Table. Distinguish between metals and non-metals on the basis of these properties.
Properties | Metals | Non-Metals |
---|---|---|
1. Appearance |
Why is the distance between stars expressed in light years? What do you understand by the statement that a star is eight light years away from the Earth?
What are sex hormones? Why are they named so? State their function.
An archer stretches her bow while taking aim at the target. She then releases the arrow, which begins to move towards the target. Based on this information fill up the gaps in the following statements using the following terms:
muscular, contact, non-contact, gravity, friction, shape, attraction
(a) To stretch the bow, the archer applies a force that causes a change in its ——.
(b) The force applied by the archer to stretch the bow is an example of ——— force.
(c) The type of force responsible for a change in the state of motion of the arrow is an example of a ———— force.
(d) While the arrow moves towards its target, the forces acting on it are due to ———— and that due to ———— of air.
Indicate whether the following statements are True (T) or False (F):
(a) Oviparous animals give birth to young ones. ( )
(b) Each sperm is a single cell. ( )
(c) External fertilization takes place in frog. ( )
(d) A new human individual develops from a cell called gamete. ( )
(e) Egg laid after fertilization is made up of a single cell. ( )
(f) Amoeba reproduces by budding. ( )
(g) Fertilization is necessary even in asexual reproduction. ( )
(h) Binary fission is a method of asexual reproduction. ( )
(i) A zygote is formed as a result of fertilization. ( )
(j) An embryo is made up of a single cell. ( )
Should the handle and bristles of a tooth brush be made of the same material? Explain your answer.
Which zone of a flame does a goldsmith use for melting gold and silver and why?
Is it safe for the electrician to carry out electrical repairs outdoors during heavy downpour? Explain.
Explain why chloroplasts are found only in plant cells?
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.