Can a sister and brother see each other naked?
Yes, it might not be good if anything comes of it though.
Can brother see his sister naked?
No. Your sister would probably feel that her privacy had been invaded. It's best not to see anyone naked until invited to do so.
In a group of siblings there are 7 sister each sister has 1 brother how many siblings are there in total?
8 siblings all together as each sister has 1 common brother.
If a brother and sister have the same mother but different father are they step brother and sister?
No here they are still brother and sister, but they do have a stepfather.
Me and my sister always get in fights where you yell and swear at each other how do we stop?
Did you tell your parents about this? If you don't want to, you could talk to your school's guidance counsellor.