Mention the unit of power in the British unit system.

The unit of angular acceleration in the $SI$ system is

Which of the following physical quantities can be used to express temperature?

Which of the following practical units of length is not correct?

Density of wood is $0.5 \, g/cm^3$ in the $CGS$ system of units. The corresponding value in $SI$ $(MKS)$ units is ........... $kg/m^3$.

The new $SI$ unit of mass $1 \, kg$ is defined in terms of the difference in the masses of two ${}^{133}Cs_{55}$ atoms. One of these atoms is in its ground state and the other is in an excited state that has a frequency of excitation close to $9.2 \times 10^9 \, Hz$. The number of atoms required to get $1 \, kg$ of mass this way is of the order of (Planck's constant = $6.63 \times 10^{-34} \, J \cdot s$; mass of proton = $1.67 \times 10^{-27} \, kg$; Avogadro number = $6.02 \times 10^{23} \, \text{particles}$; speed of light = $3 \times 10^8 \, m/s$).