Hey @Harry-Corke great question. Ranges are approximate and you will get varying quotes, and all distances are affected line-of-sight and obstacles, but however for the exam this is what is important:
2.4 GHz (lower frequency) will get a longer distances and slower speeds, up until 802.11n as it used multiple spatial streams to carry data and increased channel widths. (20 MHz to 40 MHz)
5 GHz (higher frequency) will get faster speeds but shorter distances. Also, with greater channel widths. (40, 80, 160 MHz)
Be able to identify the backwards compatibility as well for example 802.11a and .11n, are compatible or .11b, .11g, and .11n are all compatible.
Knowledge is a road to be traveled upon, not a destination to be reached~~