Mass =70 ( Mass of protons=1 ,Mass of neutrons =1, Mass of electron =0.0005(can be ignored)) Therefore, 40 +30=70 Charge= -2 ( it is taking in/attracting electrons to its shell) base on the proton number you are able to identify if it is attracting or releasing an electron, if the electron number is more than proton number then it is attracting therefore resulting in a negative charge vice versa for releasing an electron.
RBCs are disc-shaped with a flatter, concave center. This biconcave shape allows the cells to flow smoothly through the narrowest blood vessels. ... Many RBCs are wider than capillaries, but their shape provides the needed flexibility to squeeze through
