Charges of ions in a mass spectrometer

[Karagoz]

Homework Statement

In a mass spectrometer, a few ¹²₆C ions are deflected with a radius of 12.9 cm. The ions have a speed of 5.67*10^4 m/s when they enter the field. The magnetic field has a strength of 3.2*10^-2 T. The charge of these ions must be ...

SOLUTION:
We use the formula: i F=qvB = mv2/r and find q.

q= mv / rB = (14*1,66·10^-27 kg * 5,67*10^4 m/s) / (0,129m * 3,2*10^-2 T) = 3,2*10^-19 C = 2e

Homework Equations

One atomic unit is 1,66*10^-27 kg

But isn't the mass of ¹²₆C atom is ca 1.99264654*10^-26 kg, which is ca 12 atomic units? ( https://www.britannica.com/science/atomic-mass )

Where does the 14 come from in the solution?

The Attempt at a Solution

 

[gneill]

Perhaps the question was modified from Nitrogen atoms to Carbon atoms at some point but the solution was not updated to reflect this?