Which of the following ratios express pressure?

Photon is quantum of radiation with energy E = hν where ν is frequency and h is Planck’s constant. The dimensions of h are the same as that of

If Planck’s constant (h ) and speed of light in vacuum (c ) are taken as two fundamental quantities, which one of the following can, in addition, be taken to express length, mass and time in terms of the three chosen fundamental quantities?

Which of the following are not a unit of time?

Why do we have different units for the same physical quantity?