I am part of some groups where I give help to people but everytime I comment on someone's question, it appears on the newsfeed of my friends. How can I make the things I do in groups not visible for my friends?
If you are an admin of the group then change it to a Closed or Secret group, so that only group members will see the content. If you are not a group admin then ask the group admin to change it. If the group is Open then everyone can see all of the content, and Facebook may show it to your friends.