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Why do clothes dry slowly in winter?

Important Questions on Water

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Science>Chemistry>Water>Water Cycle

Useful substance in preparation of freezing mixture is

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Science>Chemistry>Water>Water Cycle

Which gas boils out first during fractional distillation of air.

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Science>Chemistry>Water>Water Cycle

When does ice melt at the same temperature $0 ° C$ (273 Kelvin), which one of the following has more energy?

EASY

Science>Chemistry>Water>Water Cycle

"Spirit kept in an open watch glass is converted into gaseous state even at room temperature". Explain.

HARD

Science>Chemistry>Water>Water Cycle

The melting point of naphthalene is

80 ° C

and the room temperature is

30 ° C

. A sample of liquid naphthalene at

100 ° C

is cooled down to the room temperature. Draw a temperature time graph to represent this cooling. In the graph, mark the region which corresponds to the freezing process.

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Science>Chemistry>Water>Water Cycle

Which of the following curves best represents the variation in density of water with temperature?

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Science>Chemistry>Water>Water Cycle

Latent heat of vaporisation is

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Science>Chemistry>Water>Water Cycle

Dry ice is

HARD

Science>Chemistry>Water>Water Cycle

An earthen pitcher used in summer cools water in it essentially by evaporation of water from its porous surface. If a pitcher carries

4 kg

of water and the rate of evaporation is

20 g

per hour, temperature of water in it decreases by

Δ T

in two hours. The value of

Δ T

is close to (ratio of latent heat of evaporation to specific heat of water is

540 ° C

)

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Science>Chemistry>Water>Water Cycle

Explain the liquefaction and zone refining method of refining of metals. (draw diagram)

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Science>Chemistry>Water>Water Cycle

The Clausius-Clayperon equation helps to calculate

HARD

Science>Chemistry>Water>Water Cycle

1 kg

of ice at

- 20^{o} C

is mixed with

2 kg

of water at

90^{o} C

. Assuming that there is no loss of energy to the environment, what will be the final temperature of the mixture? (Assume latent heat of ice

= 334.4 kJ {(kg)}^{- 1}

, specific heat of water and ice are

4.18 kJ {(kg - K)}^{- 1}

and

2.09 kJ {(kg - K)}^{- 1}

, respectively.)

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Science>Chemistry>Water>Water Cycle

A Carnot freezer takes heat from water at

0^{o} C

inside it and rejects it to the room at a temperature of

27^{o} C .

The latent heat of ice is

336 \times 10^{3} J k g^{- 1} .

If 5kg of water at

0^{o} C

is converted into ice at

0^{o} C

by the freezer, then the energy consumed by the freezer is close to :

HARD

Science>Chemistry>Water>Water Cycle

Assume that a drop of a liquid evaporates by a decrease in its surface energy so that its temperature remains unchanged. The minimum radius of the drop for this to be possible is. (The surface tension is

T

, the density of the liquid is

ρ

and

L

is its latent heat of vaporisation.)

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Science>Chemistry>Water>Water Cycle

Convert the following temperatures to the Kelvin scale:

a. $25 ° C$

b. $373 ° C$ ?

HARD

Science>Chemistry>Water>Water Cycle

Why does the temperature remain constant during the change of state?

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Science>Chemistry>Water>Water Cycle

Is evaporation an endothermic or exothermic process? Give one example to support your answer.

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Science>Chemistry>Water>Water Cycle

Define evaporation. Give an example that indicates that evaporation is an endothermic process.

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Science>Chemistry>Water>Water Cycle

The following questions based on the $P - T$ phase diagram of carbon dioxide:
At what temperature and pressure can the solid, liquid and vapour phases of $C O_{2}$ co-exist in equilibrium?
Question Image

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Science>Chemistry>Water>Water Cycle

While determining the boiling point of water in the laboratory, the beaker containing hot water accidentally fell on the hand of a student. A fellow student immediately put cold water on his hand and then placed ice cubes on his hand. He then took the student to the school dispensary for giving him first aid.
A. Define boiling point.
B. Why does temperature remain constant during boiling?
C. How does boiling differ from evaporation?
D. State the values displayed by the fellow student.

Why do clothes dry slowly in winter?

Important Questions on Water

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