give 250 MCQs of biology physics and chemistry class 9 chapter 1,5,8.
Answers
Answer:
Question 1.
Which of the following are matter ?
Chair, air, love, smell, hate, almonds, thought, cold, cold drink, smell of perfume.
Answer:
Chair, air, smell, almonds, cold drink, smell of perfume are matter. Please note that the smell whether pleasant or foul is due to the presence of some particles in air. It is therefore, a matter. Love, hate, thought and cold are simply feeling. They do not represent matter.
Question 2.
The smell of hot sizzling food reaches us several metres away. However, it is not so in case the food is cold. Explain.
Answer:
When food is sizzling hot, it releases the vapours of its contents. Since the kinetic energy of the particles is very
high in the vapour state, these particles readily mix up with the particles of air. They can reach us even at a distance of several metres. However, when the food is cold, the vapours released will be comparatively less. Moreover, their kinetic energy is also very small. Under these conditions, one has to come quite close in order to smell the contents of the food.Question 3.
A diver is able to cut through water in a swimming pool. Which property of matter does this observation show ?
(CBSE 2013)
Answer:
The observation explains the following properties of water (liquid state of matter) or any other liquid.
The inter particle forces of attraction are not very strong in water.
The inter particle spaces are somewhat large in water.
All these properties associated with the liquid state or water enable the diver to cut through water in a swimming pool.
Question 4.
What are the characteristics of the particles of matter ?
Answer:
Characteristics of the Particles of Matter
We have studied that matter is composed by particles and there are interparticle spaces as well. Let us brief by study the main characteristics of these particles supported by some activities.
Particle Size is Extremely Small
Particles are in a State of Motion
Inter Particle Attractions Keep Particles Close
Effect of Temperature on Particle Motion
Question 5.
The mass per unit volume of a substance is known as density (density = mass/volume). Arrange the following in order of increasing density :
Air, exhaust from chimneys, honey, water, chalk, cotton and iron.
Answer:
The increasing order of density for the given substances is :
Air, exhaust from chimneys, cotton, water, honey, chalk, iron.
Actually, the density of a substance depends upon the number of particles per unit volume as well as upon their mass. The number of the particles is related to their size as well as the attractive forces among them. Keeping this in view, the increasing order of density is as given above.
Explanation:
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