Answer: c. Oxygen, silicon, and aluminium
Explanation:
The common elements in the Earth's crust in order of decreasing abundance are as follows:
Oxygen: Oxygen is the most abundant element on earth's crust. It makes up 46.6%. It exists as compound of the silicate minerals. It is used for industrial, commercial and medical purposes.
Silicon: Silicon is the second most common and abundant element on the earth crust. It makes up the concentration of 27.7%. It combines with the minerals of silica to form the silicate minerals. It is used for the purpose of ceramics, cosmetics, glass and other products.
Aluminium: Aluminium is the third most common and abundant element on the earth crust. It makes up the concentration of 8.1%. The aluminum exists in the form of aluminium oxide, potassium aluminium sulfate and aluminium hydroxide. It is used for the purpose of manufacture of rockets, machinery and automobiles.
Australia/Oceania is the smallest continent
Answer:
Hornfels
Explanation:
Hornfels -
It refers to the category of metamorphic rocks that are heated and hardened by the igneous masses , is referred to as hornfels .
They are finely grained metamorphic rocks .
The temperature required for the formation of these rocks is about 1300 to 1450 degrees Fahrenheit .
These rocks are formed near lava flow , sill etc.
Hence , from the given information of the question ,
The correct answer is hornfels .
