Discuss various methods for weed control | Class 9 Science Chapter Improvement in Food Resources, Improvement in Food Resources NCERT Solutions

How are fish obtained?

What would happen if poultry birds are larger in size and have no summer adaptation capacity? In order to get small sized poultry birds, having summer adaptability, what method will be employed?

Cultivation practices and crop yield are related to environmental condition. Explain.

How do you differentiate between capture fishing, mariculture and aquaculture?

What is pasturage and how is it related to honey production?

How do plants get nutrients?

Fill in the blanks
(a) Photoperiod affect the ————.
(b) Kharif crops are cultivated from ———— to ————.
(c) Rabi crops are cultivated from———— to ————.
(d) Paddy, maize, green gram and black gram are ———— crops.
(e) Wheat, gram, pea, mustard are ———— crops.

Define
(i) Vermicompost
(ii) Green manure
(iii) Bio fertilizer

What factors may be responsible for losses of grains during storage?

What management practices are common in dairy and poultry farming?

Abdul, while driving to school, computes the average speed for his trip to be 20 km h^-1. On his return trip along the same route, there is less traffic and the average speed is 40 km h^-1. What is the average speed for Abdul’s trip?

An object of mass 40 kg is raised to a height of 5 m above the ground. What is its potential energy? If the object is allowed to fall, find its kinetic energy when it is half-way down.

A driver of a car travelling at 52 km h^-1 applies the brakes and accelerates uniformly in the opposite direction. The car stops in 5 s. Another driver going at 3 km h^-1 in another car applies his brakes slowly and stops in 10 s. On the same graph paper, plot the speed versus time graphs for the two cars. Which of the two cars travelled farther after the brakes were applied?

Fig 8.11 shows the distance-time graph of three objects A,B and C. Study the graph and answer the following questions:

          Fig. 8.11

(a) Which of the three is travelling the fastest?
(b) Are all three ever at the same point on the road?
(c) How far has C travelled when B passes A?
(d) How far has B travelled by the time it passes C?

Two objects, each of mass 1.5 kg, are moving in the same straight line but in opposite directions. The velocity of each object is 2.5 m s^-1 before the collision during which they stick together. What will be the velocity of the combined object after collision?

Soni says that the acceleration in an object could be zero even when several forces are acting on it. Do you agree with her? Why?

Two objects of masses 100 g and 200 g are moving along the same line and direction with velocities of 2 m s^-1 and 1 m s^-1, respectively. They collide and after the collision, the first object moves at a velocity of 1.67 m s^-1. Determine the velocity of the second object.

How do poriferan animals differ from coelenterate animals?

The speed-time graph for a car is shown is Fig. 8.12.

          Fig. 8.12

(a) Find how far does the car travel in the first 4 seconds. Shade the area on the graph that represents the distance travelled by the car during the period.
(b) Which part of the graph represents uniform motion of the car?

How are sol, solution and suspension different from each other?

What is meant by the term chemical formula?

You have a bag of cotton and an iron bar, each indicating a mass of 100 kg when measured on a weighing machine. In reality, one is heavier than other. Can you say which one is heavier and why?

What are the two forms of oxygen found in the atmosphere?

What is the momentum of an object of mass m, moving with a velocity v?
(a) (mv)²      (b) mv²      (c) 1⁄2 mv²      (d) mv

On heating calcium carbonate gets converted into calcium oxide and carbon dioxide.
(a) Is this a physical or a chemical change?
(b) Can you prepare one acidic and one basic solution by using the products formed in the above process? If so, write the chemical equation involved.

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?

The earth is acted upon by gravitation of Sun, even though it does not fall into the Sun. Why?

Explain how bats use ultrasound to catch a prey.

Abdul, while driving to school, computes the average speed for his trip to be 20 km h^-1. On his return trip along the same route, there is less traffic and the average speed is 40 km h^-1. What is the average speed for Abdul’s trip?

Why is it difficult to hold a school bag having a strap made of a thin and strong string?