English Medium Class 9 - CBSE Question Bank Solutions for Science

Figure15.1 shows the two crop fields [Plots A and B] have been treated by manures and chemical fertilizers respectively, keeping other environmental factors the same. Observe the graph and answer the following questions.

(i) Why does plot B show a sudden increase and then a gradual decrease in yield?

(ii) Why is the highest peak in plot A graph slightly delayed?

(ii) What is the reason for the different patterns of the two graphs?

Liquids generally have lower density as compared to solids. But you must have observed that ice floats on water. Find out why.

Which postulate of Dalton’s atomic theory can explain the law of definite proportions?

When 3.0 g of carbon is burnt in 8.00 g oxygen, 11.00 g of carbon dioxide is produced. What mass of carbon dioxide will be formed when 3.00 g of carbon is burnt in 50.00 g of oxygen? Which law of chemical combinations will govern your answer?

Where is apical meristem found?

Does the transfer of energy take place when you push a huge rock with all your might and fail to move it? Where is the energy you spend going?

How is our atmosphere different from the atmospheres on Venus and Mars?

How does the atmosphere act as a blanket?

How are clouds formed?

You have seen weather reports on television and in newspapers. How do you think we are able to predict the weather?

What are macro-nutrients and why are they called macronutrients?

How do plants get nutrients?

Compare the use of manure and fertilizers in maintaining soil fertility.

Why are manures and fertilizers used in fields?

What are the advantages of inter-cropping?

What is the value of gravitational constant G (i) on the earth, and (ii) on the moon ?

State whether the following statement is true or false :

The value of G on the moon is about one-sixth `(1/6)`of the value of G on the earth.

Fill in the following blank with suitable word :

The value of g on the earth is about………………. of that on the moon.

Is the acceleration due to gravity of earth ‘g’ a constant ? Discuss.

What is the physical state of water at 100°C.