Water - Revision Notes

 CBSE Class–VI Subject Science

Revision Notes
CHAPTER – 14
Water

WATER : NATURAL GIFT

  • Water  is an inexhaustible or renewable natural resource.
  • Three -fourths of the earth's surface is covere with water.
  • Nearly 70% of our body is made up of  water and the rest is solid matter.
  • Water is essential for life.
  • Water which is fit for human consumption is known as Fresh water or Potable water.
  • Only 2.6% of total water is fresh water.
  • Only 0.01% of the total water reaches humans and animals.

SOURCES OF WATER

  • Rain water
  • Ground water
  • Surface water
  • Rivers and streams
  • Lakes and pounds
  • Sea water

STATES OF WATER

water on the earth exists in three states : solid , liquid and gas.

WATER AND ITS FORMS

  • Ice is the solid state of water.
  • Water is the liquid state of water.
  • Vapour or steam is the gaseous state of water. 

· Water Cycle:

The cycle of processes by which water circulates between the earth's oceans, atmosphere, and land, involving precipitation as rain and snow, drainage in streams and rivers, and return to the atmosphere by evaporation and transpiration.

Water Conservation: It is the wise and judicious use of water.

Ways of conserving water:

  1. Get all leaking taps repaired.
  2. Use a bucket for taking bath instead of a shower.
  3. Collect rainwater and use it for gardening and recharging ground water.
  4.  Wash your cycles, cars, etc. with a bucket of water instead of pipes.
  5. Instead of washing the floor use a mop.

· Importance of Water:

  1. Digestion of food takes place in the stomach when food is mixed with water.
  2.  Important medium for the transportation of food, oxygen and carbon dioxide in the body.
  3. Water is used to produce electricity.
  4. Water is essential for the germination of seeds.
  5. Water helps in maintaining the body temperature.

Excess of water: When it rains or snow, some of the water is retained by soil. Its caused flood. It effects by damage property and endanger the lives of humans and animals. Rapid run-off causes soil erosion.

Lack of water: It is the lack of sufficient available water resources to meet water needs within a region. It cause drought like condition. It effect by acute water crisis, crop failure, loss of life in all forms due to starvation.

Rainwater Harvesting: Method of collecting rainwater and storing it for use during scarcity. It can be used for several purposes including drinking, washing, gardening, flushing, etc.

  • Water vapour gets added to air by evaporation and transpiration.
  • The water vapour in the air condenses to form tiny droplets of water, which appear as clouds. Many tiny water droplets come together and fall down as rain, snow or hail.
  • Rain, hail and snow replenish water in rivers, lakes, ponds, wells and soil.
  • Excessive rains may cause floods while lack of it for long periods may cause droughts.
  • The amount of usable water on earth is limited so it needs to be used carefully.