In an elastic collision
1.Energy is conserved but momentum is not
2.Momentum is conserved but energy is not
3.Neither momentum nor energy is conserved
4.Both momentum and energy is conserved

 A lens has focal length +10 cm. An object is placed at a distance 20 cm to the left of the lens. The image is

1) real and 20 cm right of the lens

2) virtual and 20 cm left of the lens

3) real and 10 cm right of the lens 

4) virtual and 10 cm left of the lens

 Measures to control plant diseases are
 1. Prophylactic
 2. Therapeutic
 3. Immunization
 4. All the three

Who among the following said that the percentage of A + G equals 50% and the percentage of T + C equals 50% ?

(1) Hershey and Chase

(2) Jacob and Monad

(3) Griffith and Niescher

(4) None of the above

Bacteria that must have organic molecules both for energy and as a source of carbon are called

(1) Chemoautotrophs

(2) Photohetrotrophs

(3) Photoautotrophs

(4) Chemoheterotrophs

Ring-porous wood is characteristic of

1) trees of tropical rain forest
2) trees of deciduous forest
3) all trees
4) alpine trees only

The electric field associated with an e.m. wave in vacuum is given by $$\vec {E} = 40\cos (kz - 6\times 10^{8}t)\hat {i}$$, where $$E, z$$ and $$t$$ in $$volt/m$$, meter and seconds respectively. The value of wave vector $$k$$ is

1) $$6m^{-1}$$
2) $$3m^{-1}$$
3) $$2m^{-1}$$
4) $$0.5m^{-1}$$

At the mid-point along the length of a long solenoid, the magnetic field is equal to x, If the length of the solenoid is doubled and the current is reduced to half, the field at the new mid-point will be nearest to:

(1) x/2
(2) x/4
(3) x
(4) 2x

Fast neutrons can easily be slowed down by

1. Applying a strong electric field
2. The use of lead shielding
3. Passing them through water
4. Elastic collision with heavy nuclei

Nerve cells are not found in
1. Sponges
2. Coelenterates
3. Nematodes
4. Mosquitoes