307426 The dimension of Planck’s constant are same as
Plank’s constant, h and angular momentum, mvr have same units kg m2s−1
307427 Ionisation energy of gaseous Na atoms is 495.5kJmol−1. The lowest possible frequency of light that ionises a sodium atom is (h=6.626×10−34Js,NA=6.022×1023mol−1)
Energy =NAhv495.5=6.023×1023×6.6×10−34×vv=495.5×103J6.023×1023×6.6×10−34=12.4×1014=1.24×1015s−1
307428 Electromagnetic radiation of wavelength 242 nm is just sufficient to ionize the sodium atom. What is the ionization energy of sodium per atom?
E=hcλ=6.62×10−34×3×108242×10−9=8.207×10−19J
307429 Excited hydrogen atom emits light in the ultraviolet region at 2.47×1015Hz. With this frequency, the energy of a single photon is: (h=6.63×10−34Js)
E=hv=6.63×10−34×2.47×1015=1.640×10−18J