density calculation

A water column of height 30 cm is supporting a 20 cm column of a liquid of density p. Calculate the value of p.

If critical frequency is 40 MHz then calculate maximum density of electron-

If critical frequency is 40 MHz then calculate maximum density of electron-

How is density of population of a region calculated?

How is density of population of a region calculated?

Calculate the density of flatrine nucleus supposing that the shape of the nucleus is spherical and its radius is 5 xx 10^(-13) (Mass of f =19 ams)