ISC (Science) ISC Class 12 - CISCE Important Questions

As a member of the Student Council of you school, you wish to start an old clothes collection drive. These clothes are to be donate to an orphanage nearby. Write a proposal in not more than 150 words, stating the steps you would take to make it a seccess. 

You are the editor of your school magazine. You have recently attended a cultural program in your city. Write an account of this program (in approximately 300 words) using the points given below:

Your uncle has promised to give you a gift of Rs. 1000/-. Write a letter thanking him for the offer, tell him how you plan to spend the money; and why you wish to spend it in this way.

If f : R → R, f(x) = x³  and g: R → R , g(x) =  2x² + 1, and R is the set of real numbers, then find fog(x) and gof (x)

If a relation R on the set {a, b, c} defined by R = {(b, b)}, then classify the relation.

Show that intensity of electric field at a point in broadside position of an electric dipole is given by:

E = `(1/(4 pi epsilon_0)) p/((r^2 + l^2)^(3//2))`

Where the terms have their usual meaning.

Arrangement of an oxygen ion and two hydrogen ions in a water molecule is shown in the figure below.

Calculate the electric dipole moment of a water molecule. Express your answer in terms of e (charge on hydrogen ions), l and θ.

State Gauss’ Law.

Draw a labelled circuit diagram of a potentiometer to measure the internal resistance ‘r’ of a cell. Write the working formula (derivation is not required). 

What happens when an electron collides with a positron?

Name the principle on the basis of which optical fibres work.

What is symbiosis?

Explain the term perianth.

Give the biological name of the following:

Baker’s yeast

State two advantages of vegetative propagation.

Give two differences between heartwood and sapwood.

Define Racemose inflorescence

Name a plant which flowers every twelve years.

Name the terminal stage of ageing in the life cycle of plants.

Give a reason for the Following:

Pollen grains of wind-pollinated flowers are produced in large quantities.