The number of neutrons in 13A127 is

The number of neutrons in an atom is determined by subtracting the atomic number (Z) from the mass number (A). In the notation 13Al27, the subscript 13 represents the atomic number, which is the number of protons in the nucleus [t1][t8]. The superscript 27 represents the mass number, which is the total sum of protons and neutrons [t1][t10]. Using the standard formula N = A - Z, where N is the number of neutrons, we calculate 27 - 13 = 14 [t6][t7]. This specific isotope of aluminum, Aluminium-27, is the only stable isotope of the element and contains 13 protons and 14 neutrons [t9][t10]. Therefore, the correct count of neutrons for this atom is 14, matching option 3.