i just need an explanation :) so the problem was " what is the mass of 5 molecules of water(H2O) , in grams?" my teacher said the answer is 1.50 x 10^-22 but i dont understand why. why is it not 1.50 x 10^24, why is the exponent negative?

Explanation:

The exponent is negative because water molecules are absolutely tiny. You can't see a molecule of water on the palm of your hand with your naked eyes, right? If a the mass of a molecule was 1.50 x 10^24, it'd be HUGE... like absolutely massive (possible the size of your city). Molecules are just tiny, tiny particles

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."

a is the answer to this question

explanation: