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Useful substance in preparation of freezing mixture is 

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Important Questions on Matter in our Surroundings

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Science>Chemistry>Matter in our Surroundings>Interconversion of Matter
Which of the following curves best represents the variation in density of water with temperature?
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Science>Chemistry>Matter in our Surroundings>Interconversion of Matter
Which gas boils out first during fractional distillation of air.
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Science>Chemistry>Matter in our Surroundings>Interconversion of Matter

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

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Science>Chemistry>Matter in our Surroundings>Interconversion of Matter
The melting point of ice is _____.
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Science>Chemistry>Matter in our Surroundings>Interconversion of Matter
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>Matter in our Surroundings>Interconversion of Matter
"Complete melting of ice cream will not happen suddenly". Explain.
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Science>Chemistry>Matter in our Surroundings>Interconversion of Matter
Latent heat of vaporisation is 
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Science>Chemistry>Matter in our Surroundings>Interconversion of Matter
Explain how is nuclear energy generated in power reactors. How is electricity produced from nuclear energy?
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Science>Chemistry>Matter in our Surroundings>Interconversion of Matter
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>Matter in our Surroundings>Interconversion of Matter
Explain the liquefaction and zone refining method of refining of metals. (draw diagram)
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Science>Chemistry>Matter in our Surroundings>Interconversion of Matter

Write down the two benefits of use of solar energy.

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Science>Chemistry>Matter in our Surroundings>Interconversion of Matter
1 kg of ice at -20oC is mixed with 2 kg of water at 90oC . 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>Matter in our Surroundings>Interconversion of Matter

Write names of any two energies produced in ocean.

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Science>Chemistry>Matter in our Surroundings>Interconversion of Matter
Dry ice is
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Science>Chemistry>Matter in our Surroundings>Interconversion of Matter
Nowadays bio-diesel is used in transportation vehicles as an alternate to diesel. Write two advantages of this measure.
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Science>Chemistry>Matter in our Surroundings>Interconversion of Matter
Which of the following is not an example of a bio-mass energy source?
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Science>Chemistry>Matter in our Surroundings>Interconversion of Matter
Uranium is used to obtain:
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Science>Chemistry>Matter in our Surroundings>Interconversion of Matter
The Clausius-Clayperon equation helps to calculate
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Science>Chemistry>Matter in our Surroundings>Interconversion of Matter
A Carnot freezer takes heat from water at 0oC inside it and rejects it to the room at a temperature of 27oC. The latent heat of ice is 336×103 Jkg-1. If 5kg of water at 0oC is converted into ice at 0oC by the freezer, then the energy consumed by the freezer is close to :
HARD
Science>Chemistry>Matter in our Surroundings>Interconversion of Matter
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.)