(a). Firstly, pull out useful information . λ=656.3nm Secondly, identify relevant equation and rearrange to find frequency. λ=c/f => f=c/λ Calculate frequency using the given values (c=3*10^8 m/s), ensuring to convert nm into m f=c/λ=(3*10^8)/(656.3*10^-9) f=4.57*10^14 Hz => as required, ensuring correct units (Hz)(b). Firstly, identify relevant equation (Planck-Einstein Relationship) and required variables. f=4.57*10^14 Hz h=6.63*10^-34 Js => Planck's Constant E=hf Then, calculate energy using the above equation E=hf=(6.63*10^-34)*(4.57*10^14) E= 3.03*10^-19J => Final answer, with correct units Joules