When two atoms with different electronegativities are bonded together, a bond exists. these are displayed with an arrow originating at the atom with the electronegativity and pointing toward the atom with the electronegativity.?

Explanation:

Electronegativity is defined as the ability of an atom to readily accept one or more number of electrons.

When this electronegative atom comes in contact with a metal or less electronegative atom then more electronegative atom readily attracts an electron. (As nucleus contains protons which hold a positive charge can easily attract an electron).

For example, fluorine is a highly electronegative atom and it readily attracts an electron from hydrogen atom when both of them comes in contact with each other.

This reaction leads to the formation of hydrogen fluoride compound.  

So basically, electron is pulled by more electronegative atom from the less electronegative atom.

Thus, we can conclude that when two atoms with different electronegativities are bonded together, a bond exists. These are displayed with an arrow originating at the atom with the less  electronegativity and pointing toward the atom with more electronegativity.

your answer would be a. 12.5 kg

b. accuracy of the data matters alot more than its number of digits, organization or amount of detail. quantitative observation is more accepted than the qualitative observation.