(a) Isotope of carbon, i.e.
13C is a natural, stable isotope of carbon with a nucleus containing six protons and seven neutrons. It make up about
1.1% of all natural carbon on Earth.
(b) On moving from top to bottom in IV A group, the melting point decreases. The decreasing order of melting point
>>>> (c) On Earth, oxygen is most common element, making up about
47% of Earth's mass. Silicon is second making up
28% followed by aluminium
(8%), iron
(5%) etc.
(d) The resistivity of semiconductors depends strongly on the presence of impurities in the material.
Carbon resistivity
(Ωm)=3×105−60×10−5 Hence, all the statements are correct.