Explain the folowing sentences.
Saving energy is the need of the hour.

Explain the following sentences: Saving energy is the need tof the hour.

Explain the following statements 'Save energy' is the need of the hour.

Explain the following sentence: Humans are ureotelic.

Explain the following sentences. Energy obtained from fossil fuels is not green energy.

Explain the following sentences: Energy obtained from fossil fuels is not green energy.

Explain the following sentence: Sharks retain more urea in their blood.

Fill in the blanks and explain the completed sentences. Refractive index depends on the ___ of light.

Explain why is modulation needed.

Explain the statemetn "Potential Energy is relative".