Which one of the following are the two main constituents of granite?
A. Iron & Nickel
B. Silica & Aluminum
C. Iron & Silver
D. Iron Oxide & Potassium
E. Potassium & Silver
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → B only
Granite is an igneous rock formed when magma cools slowly deep below the surface. It is made up mainly of the minerals quartz (silica, SiO2) and feldspar (aluminium silicates), so its two main constituents are silica and alumina (aluminium). Granite is the typical rock of the continental crust, the layer called “sial” (silica + aluminium).
A. Iron & Nickel Incorrect. Iron and nickel make up the Earth’s core (“nife”), not granite.
B. Silica & Aluminum Correct. Quartz supplies the silica and feldspar the aluminium, the two main constituents of granite.
C. Iron & Silver Incorrect. Silver is a rare metal, not a main part of any common rock.
D. Iron Oxide & Potassium Incorrect. Potassium occurs in some feldspars and iron oxide in small amounts, but they are minor parts, not the main constituents.
E. Potassium & Silver Incorrect. Silver is not a constituent of granite at all.