MEDIUM
Earn 100

Why solid carbon dioxide is called as dry ice?

Important Questions on Matter in our Surroundings

MEDIUM

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

MEDIUM
The Clausius-Clayperon equation helps to calculate
HARD
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.)
MEDIUM
Which of the following curves best represents the variation in density of water with temperature?
MEDIUM
Which gas boils out first during fractional distillation of air.
MEDIUM
Which of the following is not a pollutant?
MEDIUM
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
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 )
 
EASY
Which of the following compound can not be sublimed?
EASY
"Complete melting of ice cream will not happen suddenly". Explain.
MEDIUM
Useful substance in preparation of freezing mixture is 
EASY
Which of the following does not undergo sublimation?
MEDIUM
The following statements apply to SO2 but NOT to H2S:
MEDIUM
Explain the liquefaction and zone refining method of refining of metals. (draw diagram)
HARD
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.)
HARD
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.