The value of Planck's constant is:

• A

  $6.63 \times 10^{-34} \mathrm{Js}^{-1}$
• Correct answer
  B

  $6.63 \times 10^{-34} \mathrm{~m}^2 \mathrm{~s}^{-1}$
• C

  $6.63 \times 10^{-34} \mathrm{~kg} \mathrm{~m}^2$
• D

  $6.63 \times 10^{-34} \mathrm{~J} \mathrm{~s}^{-1}$

Hence, the correct answer is option: 'B'.