Electopositivity is the oppsosite of electronegativity. It is an element's ability to donate electrons electrons. Basically how easily something can donate electrons, and thus shows metallic character. For example, Cs is very electro-positive. It has the best ability to donate electrons. But Chlorine is not electropositive, it is electronegative and will want to pull electrons to itself.
Diamond and Graphite:
In order for this reaction to endothermic, 1 2 and 3 must be true.
2 must be true because the bonds broken (3 c-c) must have a greater bond energy than 4 c-c bonds in diamond, in order for more energy to required than given out, for the reaction to be endothermic. Becasue 3 C-C bonds are broken and 4 C-C bonds are made.
1 therefore must be true because atomisation means turning it into gaseous form, thus breaking 3C-C bonds, thus 1 is the same as 2.
3: An endothermic reaction means the material formed is less stable than its products. Thus, the enthalpy change of burning diamond should be greater than graphite, as diamond is less stable and will lose more energy than graphite.
Hope this asnwers ur q. This is by far one of the hardest qs i have answered.
