Question

1. Convert the following temperatures to the celsius scale.
(a) 293 K
(b) 470 K
2. Convert the following temperatures to the kelvin scale.
(a) 25°C
(b) 373°C.
3. Give reason for the following observations.
(a) Naphthalene balls disappear with time without leavi
any solid.
(b) We can get the smell of perfume sitting several metr
away
4. Arrange the following substances in increasing order of for
of attraction between the particles- water, sugar, oxygen.
5. What is the physical state of water at-
(a) 25°C
(b) 0°C
(c) 100°C ?
6. Give two reasons to justify-
(a) water at room temperature is a liquid.​

Answer 1

1. a) 293k = 293-273 = 20°C

b) 470k = 470-273 = 197°C

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2. a)25° = 25+273 = 298k

b)373° = 373+273 = 646k

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3. a) This is so because, napthalene balls undergoes the process of Sublimation. That is why, napthalene balls(solid) directly gets converted into gaseous state.

b)As perfume is a gas, the rate of diffusion is fastest in it. So, we can easily get a hint from this point that as gases have the highest rate of diffusion, the smell of perfume reaches to us from one corner to another corner of room

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4. oxygen › water › sugar

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5. a)Water at 25°C (298k) is present in liquid state.

b)At 0°C, water can exist at both solid and liquid state. At this temperature, after getting the heat equal to the latent heat of fusion, the solid form of water i.e, ice starts changing into it's liquid form i.e water.

c)At 100°C, water can both exist in both liquid and gaseous state. At this temperature, after getting the heat equal to the latent heat of vaporisation, water starts changing from its liquid state to it's gaseous state, i.e water vapours.

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6. a) water at room temperature (25°C) is considered to be liquid as because of the following reasons:-

i) at room temperature water flows

ii) at room temperature it has a fixed volume but not a definite shape. It changes into the shape of the container in which it is kept.

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