Three isotopes of an element have mass numbers m, (m + 1) and (m + 2). If the mean mass number is (m + 0.5) then which of the following ratios may be accepted for m,(m + 1) (m + 2) in that order?

Three isotopes of an element have mass numbers m, (m + 1) and (m + 2).

1.	Three isotopes of an element have mass numbers m, (m + 1) and (m + 2). If the mean mass number is (m + 0.5) then which of the following ratios may be accepted for m,(m + 1) (m + 2) in that order?
Answer» `1:1:1` `4:1:1` `3:2:1` `2:1:1` ANSWER :B