Let the tension in the string be denoted by T and the acceleration of the system by a. For particle A (mass 0.8 kg), applying Newton's second law gives:

\(8 - T = 0.8a\)

For particle B (mass 0.2 kg), applying Newton's second law gives:

\(T - 2 = 0.2a\)

Adding these two equations to eliminate T:

\((8 - T) + (T - 2) = 0.8a + 0.2a\)

\(6 = a\)

Thus, the acceleration a is 6 m s^-2.

\(Substitute a = 6 into the equation for particle B:\)

\(T - 2 = 0.2(6)\)

\(T - 2 = 1.2\)

\(T = 3.2\)

Therefore, the tension in the string is 3.2 N.