Class 9th - Science
TOP 25 QUESTIONS
, CHEMISTRY
Q1.(a) When a crystal of potassium permanganate is placed in a beaker of water, its
purple color spreads throughout. What does this observation conclude about
potassium permanganate and water?
(b)What do you understand by the term ‘latent heat of fusion’? How much is the latent
heat of fusion of ice?
(c)Substance ‘A’ has high compressibility and can be easily liquefied. It can take up the
shape of any container. Predict the nature of the substance. Enlist four properties of
this state of matter.
,(a) The purple color spreading throughout the water indicates diffusion. Potassium permanganate, being a solid,
initially settles at the bottom, but water molecules collide with it and the particles intermingle due to sufficient space
between the molecules in the liquid state.
(b) The amount of heat required to convert 1 kg of a solid into a liquid at atmospheric pressure, without any change in
temperature at its melting point, is called the latent heat of fusion.
The latent heat of fusion of ice in SI units is 3.35 × 10⁵ J/kg.
(c) Substance ‘A’ is a gas.
Properties of gases:
They do not have a fixed shape or a fixed volume.
They have a large interparticle space.
They experience the least force of attraction between molecules.
They are highly compressible.
, CHEMISTRY
Q2. (a)Convert the following temperature to Celsius scale:
a. 300K
b. 573K
(b)Comment on the following statements:
i. Evaporation causes cooling.
ii. Rate of evaporation of an aqueous solution decreases with increase in humidity.
iii. Sponge though compressible is a solid.
iv. Ice is solid at 0°C, while water is liquid at room temperature.
v. Sugar crystals dissolve faster in hot water than cold water.
TOP 25 QUESTIONS
, CHEMISTRY
Q1.(a) When a crystal of potassium permanganate is placed in a beaker of water, its
purple color spreads throughout. What does this observation conclude about
potassium permanganate and water?
(b)What do you understand by the term ‘latent heat of fusion’? How much is the latent
heat of fusion of ice?
(c)Substance ‘A’ has high compressibility and can be easily liquefied. It can take up the
shape of any container. Predict the nature of the substance. Enlist four properties of
this state of matter.
,(a) The purple color spreading throughout the water indicates diffusion. Potassium permanganate, being a solid,
initially settles at the bottom, but water molecules collide with it and the particles intermingle due to sufficient space
between the molecules in the liquid state.
(b) The amount of heat required to convert 1 kg of a solid into a liquid at atmospheric pressure, without any change in
temperature at its melting point, is called the latent heat of fusion.
The latent heat of fusion of ice in SI units is 3.35 × 10⁵ J/kg.
(c) Substance ‘A’ is a gas.
Properties of gases:
They do not have a fixed shape or a fixed volume.
They have a large interparticle space.
They experience the least force of attraction between molecules.
They are highly compressible.
, CHEMISTRY
Q2. (a)Convert the following temperature to Celsius scale:
a. 300K
b. 573K
(b)Comment on the following statements:
i. Evaporation causes cooling.
ii. Rate of evaporation of an aqueous solution decreases with increase in humidity.
iii. Sponge though compressible is a solid.
iv. Ice is solid at 0°C, while water is liquid at room temperature.
v. Sugar crystals dissolve faster in hot water than cold water.
