List of top Questions asked in CBSE Class IX

Factorise: 

(i) 4x 2 + 9y 2 + 16z 2 + 12xy – 24yz – 16xz 

(ii) 2x 2 + y 2 + 8z 2 – 2√2 xy + 4√2 yz – 8xz

Evaluate the following using suitable identities: (i) (99)3 (ii) (102)3 (iii) (998)3

Write the following cubes in expanded form: 

(i) (2x + 1)3 (ii) (2a – 3b) 3 (iii) [\(\frac{3}{2}\) x + 1]3 (iv) [x - \(\frac{2 }{ 3} \)y]3

Factorise each of the following: 

(i) 8a 3 + b 3 + 12a 2b + 6ab2 

(ii) 8a 3 – b 3 – 12a 2b + 6ab2 

(iii) 27 – 125a 3 – 135a + 225a 2 

(iv) 64a 3 – 27b 3 – 144a 2b + 108ab2 

(v) 27p 3 – \(\frac{1}{ 216}\) – \(\frac{9 }{ 2}\) p2 + \(\frac{1 }{4}\) p

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?
Verify : (i) x 3 + y 3 = (x + y) (x 2 – xy + y 2 ) (ii) x 3 – y 3 = (x – y) (x 2 + xy + y 2 ).
A battery lights a bulb. Describe the energy changes involved in the process.

Factorise each of the following: 

(i) 27y 3 + 125z 3 

(ii) 64m3 – 343n 3 

[ Hint : See Question 9. ]

Identify the type of tissue in the following:
skin, bark of tree, bone, lining of kidney tubule, vascular bundle.
Explain any one method of crop production which ensures high yield.
A mass of 10 kg is at a point A on a table. It is moved to a point B. If the line joining A and B is horizontal, what is the work done on the object by the gravitational force? Explain your answer.
Why are manure and fertilizers used in fields?
The potential energy of a freely falling object decreases progressively. Does this violate the law of conservation of energy? Why?
What are the advantages of inter-cropping and crop rotation?
In the following example, try to identify the number of times the velocity of the ball changes: “A football player kicks a football to another player of his team who kicks the football towards the goal. The goalkeeper of the opposite team collects the football and kicks it towards a player of his own team”. Also identify the agent supplying the force in each case.
What is genetic manipulation? How is it useful in agricultural practices?
Name the regions in which parenchyma tissue is present.
What are the various energy transformations that occur when you are riding a bicycle?
How do storage grain losses occur?
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?
Explain why some of the leaves may get detached from a tree if we vigorously shake its branch.
What are the benefits of cattle farming?
A certain household has consumed \(250\) \(units\) of energy during a month. How much energy is this in joules?
For increasing production, what is common in poultry, fisheries and bee-keeping?
Why do you fall in the forward direction when a moving bus brakes to a stop and fall backwards when it accelerates from rest?