The up quark u has charge +2/3 and strangeness 0; the down quark d has charge -1/3 and strangeness 0; the strange quark s has charge -1/3 and strangeness -1.This means there can be no meson with:

Question

Quizplus · Accepted Answer

To form a meson, a quark and antiquark must combine. The charge of a meson is the sum of the charges of the quark and antiquark, and the strangeness is the sum of the strangeness of the quark and antiquark. For example, the meson made of an up quark and an anti-down quark (u̅) would have a charge of (+2/3) + (-1/3) = +1/3 and a strangeness of 0.
Therefore, to have a meson with strangeness -1, one of the quarks must be a strange quark and the other must be an anti-strange quark (s̅). The charge of the resulting meson can be calculated based on the charges of the two quarks: 
charge = (+2/3) + (-1/3) = +1/3 or 
charge = (-1/3) + (+1/3) = 0. 
Therefore, only choices C and E are possible. However, a meson with a charge of +1 cannot be formed because there is no quark with a charge of +4/3. Therefore, the best choice is C.

The Up Quark U Has Charge +2/3 and Strangeness 0;