also, is it true if u your hsc mark is lower then internal u get scaled down
Naturally, a lower HSC exam mark will result in a lower overall HSC mark in the subject, since the HSC exam mark contributes 50% of the overall HSC mark. The same applies to the Assessment Mark (internal mark), i.e. a lower Assessment Mark (which also contributes 50% of the overall HSC mark) will also result in a lower overall HSC mark in the subject.
Technically, a lower Assessment Mark would result in lower scaling, although this does not mean that the Assessment Mark itself has some kind of special effect on scaling. Instead, a lower Assessment Mark simply contributes to a lower overall HSC mark (as mentioned above), which in turn leads to less favourable scaling (because the overall performance in the subject is of a lower standard).