Identify the type of fundamental interactions associated with the exchange particles in the table.

State why \({\pi ^ + }\) mesons are not considered to be elementary particles.

Identify the exchange particle associated with this decay.

Deduce that this decay conserves baryon number.

electromagnetic;

strong;

they are composed of more than one quark;

\({W^ + }\);

u has a baryon number of \(\frac{1}{3}\) and \({\rm{\bar d}}\) has a baryon number of \( - \frac{1}{3}\) ;

\({\mu ^ + }\) and \({v_\mu }\) both have a baryon number of 0;

(a)(i) was well answered.

(a)(ii) was well answered.

Most answers to (b)(ii) used quark baryon numbers of 1 etc, not \(\frac{1}{3}\).