Brazen means bold, shameless, etc. So, its antonym is bashful which means shy, timid, etc.
Malodorous means bad-smelling. Its antonym is fragrant which means smelling sweet or pleasant.
Fresh means new, clean, etc. So, its antonym is stale which means decayed, old, etc.
Expound means to explain, to talk about, etc. So, its antonym is 'confuse,' which means to confuse or confound.
'Untruthful' means dishonest etc. So, its antonym is honest which means truthful.