Fill in the Blanks:
The air is a ______________ of gases, dust particles, and water vapour.

Academic Biology NCERT Class 7

The air is a mixture of gases, dust particles and water vapour.

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Updated on: 26-Apr-2023

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Clouds are(a) tiny drops of water floating in air(b) mixture of dust and water vapour(c) particles of water vapour(d) rain drops in air.
The components of air which are harmful to living beings are(a) nitrogen and carbon dioxide(b) dust and water vapour(c) dust and smoke(d) smoke and water vapour
How will you demonstrate that water vapour is present in the air?
Fill in the blanks:The common point of a tangent and the circle is called ……….
Consider the following statements and choose the correct one:(a) We know that air or atmosphere always contains some water vapour or moisture in it.(b) Humidity is a measure of water vapour or moisture in air.(c) When the amount of water vapour in the air is high, we say humidity is high and the air feels moist or damp.(d) All the above.
How will you demonstrate that water vapour is present in air?
Fill in the blanks:The mixture of solute and solvent is called as ______.
Transpiration is a process in which plants(a) receive water from soil(b) absorb water vapour from air(c) prepare food from water(d) release water vapour.
Fill in the blanks:The longest chord of a circle is a ……… of the circle.
Which of the following statements are “true”?(a) Water vapour is present in air only during the monsoon.(b) Water evaporates into air from oceans, rivers and lakes but not from the soil.(c) The process of water changing into its vapour is called evaporation.(d) The evaporation of water takes place only in sunlight.(e) Water vapour condenses to form tiny droplets of water in the upper layers of air where it is cooler.
Fill in the blanks:The common point of a tangent to a circle and the circle is called ………...
What is the colour of the sunlight:(a) scattered by the dust particles in the atmosphere? (b) scattered by the air molecules in the atmosphere?
Does the force of gravity act on dust particles?
When a gas jar containing air is inverted over a gas jar containing bromine vapour, the red-brown bromine vapour diffuses into air. Explain how bromine vapour diffuse into air.
When a gas jar containing colourless air is kept upside down over a gas jar full of brown-coloured bromine vapour, then after some time, the brown colour of bromine vapour spreads into the upper gas jar making both the gas jars appear brown in colour. Which of the following conclusion obtained from these observations is incorrect?(a) bromine vapour is made of tiny particles which are moving(b) air is made up of tiny particles which are moving(c) the particles of bromine are moving but those of air are not moving(d) even though bromine vapour is heavier that air, it can move up against gravity

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