Write a note on how forests influence the quality of our air, soil and water resources.
Forests influence the quality of our air, soil, and water resources in various ways.
Some of them are:
(i) Adds nutrients to the soil due to the lot of vegetation present in the forest getting decomposed . Water : Forest helps in bringing rain and increasing the level of water in the underground and water bodies.
(ii) Forests prevent soil erosion. Roots of plants bind the soil tightly in a way that the surface of the soil cannot be eroded away by wind, water, etc.
(iii) Forests maintain the oxygen level in the atmosphere and also reduce the carbon dioxide level. Forests maintain the temperature of the environment.
List any three human activities that you think would lead to air pollution.
What causes winds?
Why is the atmosphere essential for life?
Why do organisms need water?
Why is water essential for life?
We know that many human activities lead to increasing levels of pollution of the air, water-bodies and soil. Do you think that isolating these activities to specific and limited areas would help in reducing pollution?
List any three human activities which would lead to an increase in the carbon dioxide content of air.
How does the atmosphere act as a blanket?
How is our atmosphere different from the atmospheres on Venus and Mars?
You have seen weather reports on television and in newspapers. How do you think we are able to predict the weather?
Which of the following has more inertia: (a) a rubber ball and a stone of the same size? (b) a bicycle and a train? (c) a five-rupees coin and a one-rupee coin?
State the universal law of gravitation.
Which of the following are matter?
Chair, air, love, smell, hate, almonds, thought, cold, cold-drink, smell of perfume.
A force of 7 N acts on an object. The displacement is, say 8 m, in the direction of the force (Fig. 11.3). Let us take it that the force acts on the object through the displacement. What is the work done in this case?
What is meant by a pure substance?
How does the sound produced by a vibrating object in a medium reach your ear?
In a reaction, 5.3 g of sodium carbonate reacted with 6 g of ethanoic acid. The products were 2.2 g of carbon dioxide, 0.9 g water and 8.2 g of sodium observations are in agreement with the law of conservation of mass.
sodium carbonate + ethanoic acid → sodium ethanoate + carbon dioxide + water
What are canal rays?
State any two conditions essential for good health.
Who discovered cells, and how?
What are the various energy transformations that occur when you are riding a bicycle?
A stone is released from the top of a tower of height 19.6 m. Calculate its final velocity.
When a carpet is beaten with a stick, dust comes out of it. Explain.
A bus starting from rest moves with a uniform acceleration of 0.1 m s-2 for 2 minutes. Find (a) the speed acquired, (b) the distance travelled.
The frequency of a source of sound is 100 Hz. How many times does it vibrate in a minute?
What are the advantages of inter-cropping and crop rotation?
How are the wavelength and frequency of a sound wave related to its speed?
What is the audible range of the average human ear?
A submarine emits a sonar pulse, which returns from an underwater cliff in 1.02 s. If the speed of sound in salt water is 1531 m/s, how far away is the cliff?
What is the utility of tissues in multi-cellular organisms?