Question

what are fundamental units?State how metre has been defined in terms of wavelength and second in terms of periods of radiation.

Answer 1

Fundamental quantities or base quantities are quantities that cannot be expressed in terms of any other physical quantities .These are length ,mass,time,electric current ,temperature, luminous intensity and amount of substance

one metre: One metre is the length of the path travelled by light in vacuum in 1/299,792,458 of a second.

One second: One second is the duration of 9,192,631,770 periods of radiation corresponding to the transition between the two hyperfine levels of the ground state of Cesium -133 atom.
Is this enough???

Answer 2

Fundamental units r those units which can neither be derived from one another nor can they be resolved into any other unit.