How many orbitals are there in the third shell (n=3)? express your answer numerically as an integer?

Answer is: there are nine orbitals in the n = 3 shell, 3² = 9.
Principal quantum number (n) describes the size of the orbital. There are one s orbital (angular quantum number l=0), three p orbitals (angular quantum number l=1 and magnetic quantum number m = -1,0,+1) and five d orbitals (angular quantum number l=2 and magnetic quantum number m = -2,-1,0,+1,+2).

The density of water is 1 g/cm cubed and in order for the pebble to sink its density has to be greater than the density of water and in order for the twig to float its density has to be less than the density of water