Many elements have non-intergral atomic masses because
(1)the constituents neutrons, protons, and electrons, commbine to give fractional masses
(2) they have isotopes
(3) their isotopes have nonintergal masses
(4) their isotopes have different masses

Options

A. `(i),(ii),(iii),(iv)`
B. `(ii),(iii),(iv)`
C. `(ii),(iv)`
D. `(iii),(iv)`

Answer

B

Explanation

Many element occur in nature as mixtures of isotopes. The atomic mass (weight) of such an element is the weighted average of the masses of its isotopes. Thus, atmoic masses are fractional numbers, not integers. For example, `{:(Isot ope,%Abundance,Mass(am u),,),(._(12)^24Mg,78.99,23.98504,,),(._(12)^25Mg,10.00,24.98584,,),(._(12)^(26)Mg,11.01,25.98259,,):}`
Atomic mass (weight)
`=(0.7899)(23.98504u)+(0.1000)(24.98584) +(0.1101) (25.98259u)`
`=18.946u+2.4986u+ 2.860u`
`= 24.30u` (to four significant figures)