protons and electrons are both always the atomic number which is 9 in this case.
For neutrons you subtract the atomic number (9) from the weight of the atom (18.998) some teachers will want you to round to the nearest whole (19). We do this because the number of protons is the atomic number so if you subtract the protons from the whole weight of the atom you would have the electrons and neutrons left. Since electrons weigh so little we don't have to subtract them. Weighing neutrons and electrons would be like weighing an elephant (neutrons) and then putting one marshmallow on the scale (electron).
The answer is c.diffusion.
Diffusion is the movement of ions, molecules or atoms form high concentration to low concentration across the membrane without the need of any energy or any membrane gates. The oxygen enters the alveoli will be dissolved in the water vapor that is present on the wall of the alveoli and will diffuse directly to the blood across the alveolar membrane.
<span>aluminium phosphide AlP</span>
