What will be the easiest way to convert from Hexadecimal to Octal and vice versa from Octal to Hexadecimal?

Imagine that you own a property that is exactly 2.2 acres large. you want to sell your property, but your realtor tells you that you cannot sell your land by the acre. in order to sell your land you need to determine the area you own in units of square meters? given that there are 1.6 kilometers in 1 mile and 640 acres in 1 square mile, what is the area of land that you own in square meters square meters?

What is the number of moles of chemical units represented by 9.03x10^24? and how do i show work? (dumb it down )

Three alkali metals in group 1 are a. calcium, strontium, barium b. boron, aluminum, gallium c. sodium, potassium, rubidium d. fluorine, iodine, chlorine