TS EAMCET 4-Aug-2021 Shift 1 Question Paper

(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

3550∘C

>‌

Si

1414∘C

>‌

Ge

938∘C

>‌

Pb

327∘C

>‌

Sn

232∘C

(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.