Matter in Our Surroundings – Science – (NCERT Solutions for Class 9)
- Which of the following are matters?
Chair, air, love, smell, hate, almonds, thought, cold, cold-drink, smell of perfume.
- Give reasons for the following observation
The smell of hot sizzling food reaches you several meters away, but to get the smell from cold food you have to go close.
- A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
- What are the characteristics of the particles of matter?
- The mass per unit volume of a substance is called density. (Density = mass/volume).
Arrange the following in order of increasing density–
Air, exhaust from chimneys, honey, water, chalk, cotton and iron.
- (a) Tabulate the differences in the characteristics of states of matter.
(b) Comment upon the following:
Rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy and
- Give reasons:
(a) A gas fills completely the vessel in which it is kept.
(b) A gas exerts pressure on the walls of the container.
(c) A wooden table should be called a solid.
(d) We can easily move our hand in air but to do the same through a solid block of wood we need a karate expert.
- Liquids generally have lower density as compared to solids. But you must have observed that ice floats on water. Find out why?
- Convert the following temperature to Celsius scale (a) 300 K (b) 573 K
- What is the physical state of water at (a) 250°C (b) 100°C ?
- For any substance, why does the temperature remain constant during the change of state?
- Suggest a method to liquefy atmospheric gases.
- Why does a desert cooler cool better on a hot dry day?
- How does the water kept in an earthen pot (matka) become cool during summer?
- Why does our palm feel cold when we put some acetone or petrol or perfume on it?
- Why are we able to sip hot tea or milk faster from a saucer rather than a cup?
- What type of clothes should we wear in summer?
- Convert the following temperatures to the Celsius scale. (a) 293 K (b) 470 K
- Convert the following temperatures to the kelvin scale. (a) 25°C (b) 373°C
- Give reason for the following observations.
(a) Naphthalene balls disappear with time without leaving any solid.
(b) We can get the smell of perfume sitting several meters away.
- Arrange the following substances in increasing order of forces of attraction between the particles-water, sugar, oxygen.
- What is the physical state of water at (a) 25°C (b) 0°C (c) 100°C ?
- Give two reasons to justify
(a) Water at room temperature is a liquid.
(b) An iron almirah is a solid at room temperature.
- Why is ice at 273 K more effective in cooling than water at the same temperature?
- What produces more severe burns, boiling water or steam?
- Name A, B, C, D, E and F in the following diagram showing change in its state.