Your question isn't quite clear, but if you're wondering if a chemical is polar or non-polar, you simply draw a VSEPR sketch and draw arrows where the bonds are. Only draw arrows between atoms, NOT between an atom and a lone pair of electrons. The arrow should point to the most electronegative atom (you should be given an electronegativity scale). Afterwards, you add up the arrows as vectors, and look at the sum of the vectors. If the sum is zero (CH4 is a good example), the chemical is non-polar. If the sum is a vector, the chemical is polar (H2O, or water, is polar).
Answer and Explanation:
Ions are electrically charged particles that are formed from the removing and addition of electrons. It can be a positively or negatively charged atom.
It is too early for students to have career preferences while still in school
(i believe) <span />
40.0 g ( 1 mole ) --------------- 6.02x10²³ molecules
? ? --------------------------- 2.90x10²² molecules
mass = 2.90x10²² * 40.0 / 6.02x10²³
mass = 1.16x10²⁴ / 6.02x10²³
mass = 1.9269 g
hope this helps!