# Number of planes with maximum atoms

Number of planes in $$\text{SiH_2FCl}$$ which contain maximum atoms but all must be different?

I am interested in the above problem. I predicted the answer to $$10$$ which indeed is $$5\choose 3$$ because maximum number of points in a plane will be $$3$$ since the structure is tetrahedral. But the book writes an answer $$7$$ to the above problem!! Any help will be highly appreciated.

I predicted the answer to 10 which indeed is $$5\choose 3$$ because maximum number of points in a plane will be 3 since the structure is tetrahedral.