2011 1.2

1.2 Which of the following rocks contributes to the highest amount of radioactive heat in the earth’s crust?

(A) basalt

(B) gabbro

(C) dunite

(D) Granite

GRANITE: It mainly consists of a larger part of earth crust and mostly contain alkali feldspar (K- felds part) & Quartz with small amount of other accessory minerals Since K (potassium) is a radioactive element because of its hight abundancy contributes to the highest amount of radioactive heat in the earth crust