It can be and is.
Yes.
The greatest common factor can't be a smaller number than the least common factor, but if you meant least common multiple, 7 and 28 have a GCF of 7 and an LCM of 28.
254 cannot have a greatest common factor. To have a greatest common factor, there must be more than one number involved
There is no common factor as you have to have at least 2 numbers to have a "common" factor. The greatest factor of 225 other than 225 is 75
No. The smallest coefficient possible is 1, and the smallest GCF is also 1. You cannot have a common factor of zero.
Well, not always. The GCF and LCM of 10 and 10 is 10. But apart from that special circumstance, the statement is true. Apart from a number itself, all of its factors are smaller than it. Apart from a number itself, all of its multiples are larger than it. You can't have a GCF that is greater than the smaller number, and you can't have an LCM that is less than the larger one which means that the LCM of two numbers will never be less than the GCF. Factors go into numbers, numbers go into multiples.
Since 2 is a factor of 4a and the largest factor of 2 is 2, and thus the greatest common factor cannot be larger than 2, the greatest common factor is 2.
No, it is never bigger than the smaller number.
No, it is never bigger than the smaller one.
Always equal to or less than the smaller number, yes.
Yes, the greatest common factor is less than or equal to the smallest coefficient. For example, the greatest common factor of 38 and 8 is 2.
They have no common factor other than 1.