About Nose weight of the centre-axle trailer: which statement is WRONG?
The 50 kg maximum applies specifically to a centre-axle trailer WITH A MASS OF AT MOST 750 KG.
The nose-weight requirements (max. 50 kg / min. 1% TMM) apply to every trailer, regardless of type.
There is no '75 kg' in the book. Up to 750 kg TMM a maximum of 50 kg applies; above 750 kg TMM a minimum of 1% of the permitted maximum mass applies. '75 kg' is a quick-prep rule of thumb, not a book limit.
Explanation
trap: overgeneralisation. Book p.230 - the text literally refers to 'the load under the coupling of a centre-axle trailer'. This atom is limited to that type