How can i get along better with my mom?

My mom always wants me to watch my younger brother and sister , literally all the time.When i try to tell her she just yells at me and calls me a lair.I don't get to spend any time with her anymore and she keeps yelling at me.I don't now what to do.I'm always studying and ive been getting good grades and also havebeen trying to be a good sport.But she still yells at me. Can any1 help?? i want a good relationship with my mom i just don't know what to do anymore.