The known forces of nature can be divided into four classes, viz, gravity electromagnetism, weak nuclear force and strong nuclear force. with reference to them, which one of the following statements is not correct?

Which of the following leaf modifications occurs/occur in desert areas to inhibit water loss?

1. Hard and waxy leaves 
2. Tiny leaves or no leaves 
3. Thorns instead of leaves

Select the correct answer using the codes given below. 

Which of the following statements is / are correct?
1. Viruses lack enzymes necessary for the generation of energy.
2. Viruses can be cultured in any synthetic medium.
3. Viruses are transmitted from one organism to another by biological vectors only.
Select the correct answer using the codes given below.

Many transplanted seedlings do not grow because

Rainbow is produced when sunlight falls on drops of rain.
Which of the following physical phenomena are responsible for this?

1. Dispersion 
2. Refraction 
3. Internal reflection

Select the correct answer using the codes given below. 

Consider the following phenomena:
1. Size of the sun at dusk
2. Colour of the sun at dawn
3. Moon being visible at dawn
4. Twinkle of stars in the sky
5. Polestar beingvisible in the sky

Which of the above are optical illusions?