One lunar cycle is nearly equal to:

1. 28.5 days
2. 29.5 days
3. 30 days
4. 30.5 days

One shake is equal to:

1. 10^-9 s
2. 10^-8 s
3. 10^-10 s
4. 10⁸ s

Which one of the following is a derived unit?

1. Metre
2. Kelvin
3. Metre³
4. Mole

The S.I. unit of energy is:

1. Joule
2. Kg m²
3. Kg m²s^-3
4. Kg m²s^-1