ON THE BASIS OF POSITION OF CENTROMERE
The centromere is located at the centre of the chromatids and arms on either side of centromere are equal in length.
The centromere is located slightly away from the centre. This results in formation of arms of unequal length.The smaller arm is called p-arm and the longer arm is called q-arm.
The centromere is located far from the centre and close to the telomere. In Acrocentric chromosomes, the difference in length of the arms is more as compared to Sub-metacentric chromosomes. (p<<q)
The centromere is located at the terminal part of the chromosomes.