The numerator must contain the unit INTO which you are converting.
The denominator must contain the unit that you wish to cancel in the numerator of the other number.
The unit that is used in the denominator is the one to cancels the unit that appears in a numerator.
It is the units for the measurement which you are converting FROM.
These are the units which are used for the measurement that you are converting FROM.
Assuming you are talking about stoichiometery a conversion factor is often a number with two units. For example a conversion factor could be Miles per hour (Miles/hour). If you had miles and needed to convert to hours you would multiply the miles by Hours/miles so that the miles would be canceled out (miles/miles = 1). Then your units left would be hours. Or vice versa. There are other factors like this in chemistry like grams/mol Mol/liter etc. To put it shortly the conversion factor denominator is always paired with the numerator.
For a fraction to be in its simplest form, numerator and denominator must have no common factor.
The unit that is used in the denominator is the one to cancels the unit that appears in a numerator.
It must be the unit of the measurement that you are converting FROM.
No. It would be very unusual for a conversion factor to equal one.
It is 1.
The measurements must be equal to each other.
The conversion factor, for converting from UNITA to UNITB is the number of UNITB in each UNITA. There are 3.2808 feet in 1 metre so the conversion factor for converting metres into feet is 3.2808.