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Subject :NSO    Class : Class 10

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Subject :NSO    Class : Class 7

Consider the following statements. Select the option which correctly identifies true (T) and false (F) ones.
(i) Animals found in understorey include frogs, lizards, snakes, insects, monkeys etc.
(ii) Vegetation that grows under the shade of tall trees is called crown.
(iii) The canopy layer of forests intercepts the flow of rain.
(iv) The tall trees of emergent layer gets a lot of sunlight.

(i) (ii) (iii) (iv)
A T F T F
B F T F T
C T F T T
D T F F T


Ans 1:

Class : Class 7
Ans is C

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Subject :NSO    Class : Class 3

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Subject :NSO    Class : Class 3

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Subject :NSO    Class : Class 8

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Subject :NSO    Class : Class 5

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Subject :NSO    Class : Class 6

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Subject :NSO    Class : Class 6

_________ is a hard grey metallic element with a very _________ melting point, used to make bulb filaments.
An electric bulb is filled with an _________, so that the filament doesn't burn up when it gets hot.

A Nickel, high, nitrogen
B Iron, high, oxygen
C Tungsten, high, inert gas
D Tungsten, low, inert gas


Hi. Answer to this question is c. , as tungsten is used because nickel and iron have high melting points and cannot be suitable for bulbs. Tungsten has a high melting point. It is filled with neon/hydrogen/helium or any inert gas in order the filament does not get burned, as inert gases are unreactive.

Ans 1:

Class : Class 6

Ans 2:

Class : Class 7
Let’s read the following lines and fill up the blanks: Tungsten is a hard grey metallic element with a very High melting point, used to make bulb filaments. An electric bulb is filled with an Inert Gas, so that the filament doesn't burn up when it gets hot. The filament used in an electric bulb has to get heated up to a very high temperature in order to emit light. At the same time, it should have a very high melting point; otherwise it would melt when electricity passes through it and the bulb would become useless. Tungsten is used as the filament in incandescent light bulbs because it has the highest melting point of any metal (> than 3400°C). Electric bulbs can't be filled with air as the filament in the bulb (tungsten) will react with oxygen and the filament will burn. So, electric bulbs are filled with inert gases like argon, as it prevents evaporation of filament and maintains the pressure inside the bulb. Hence, the right answer is Option C.

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Subject :NSO    Class : Class 9

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Subject :NSO    Class : Class 9

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