Which among the following statements with respect to carbon is/are correct?

1. Carbon forms the basis for all living organisms and many things we use

2. Carbon shows tetra-valency and the property of catenation

3. Carbon forms covalent bonds with itself and other elements

4. Carbon forms compounds containing triple and tetra bonds between carbon atoms

Select the correct answer using the code given below:

Which one of the following graphs represents the equation of motion v = u + at; where all quantities are non-zero and symbols carry their usual meanings?

Which one of the following statements is true for sound waves propa- gating in air?

A 100 g sphere is moving at a speed of 20 m/s and collides with another. sphere of mass 50 g. If the second sphere was at rest prior to the collision and the first sphere comes at rest immediately after the collision, considering the collision to be elastic, the speed of the second sphere would be