Acarbonatomhasarelativeatomicmassof12.8.60%ofthecarbonatomhasamassnumberof12.4.30%ofthecarbonatomshaveamassnumberof13.4,whilsttheremaining10%haveamassnumberwhichisnotknown.Calculatethemassnumberofthecarbonisotopewhichis10%oftheCarbon12.8atom.Giveyouranswerto1decimalplace,ifneeded.

The question is asking for the mass number of the carbon isotope that makes up 10% of the Carbon-12.8 atom.

First, let's break down the information given:

• 60% of the carbon atom has a mass number of 12.4
• 30% of the carbon atom has a mass number of 13.4
• 10% of the carbon atom has an unknown mass number

We know that the relative atomic mass of the carbon atom is 12.8. The relative atomic mass is the weighted average of the atomic masses of the isotopes, so we can set up the following equation:

(0.60 * 12.4) + (0.30 * 13.4) + (0.10 * x) = 12.8

Where x is the mass number of the unknown isotope.

Solving for x:

7.44 + 4.02 + 0.10x = 12.8 0.10x = 12.8 - 7.44 - 4.02 0.10x = 1.34 x = 1.34 / 0.10 x = 13.4

So, the mass number of the carbon isotope that makes up 10% of the Carbon-12.8 atom is 13.4.