Question

The most abundant metal in the earth crust is:
A. Copper
B. Silver
C. Aluminum
D. Silicon

Answer 1

Hint: The most abundant metal in the earth crust has an atomic number of 13.

Step by step answer:
Aluminium is the third most abundant element and the most abundant metal in the earth crust. It forms 8.3 % of the earth's crust. It is a constituent of clay, plate and many types of silicate rocks. It is found only in the combined state.
Aluminium is mainly isolated from bauxite ore which is generally contaminated with ferric oxide and silica. The removal of ferric oxide and silica from bauxite ore is essential before it is subjected to electrolysis because it is rather difficult to remove iron and silicon from aluminium metal, the presence of these elements makes the aluminium metal brittle and liable to corrosion. Thus, the extraction of aluminium from bauxite ore involves the following three steps. (i) Purification of bauxite ore, i.e., removal of ferric oxide and silica. (ii) Electrolytic reduction of \[A{{l}_{2}}{{O}_{3}}\]. (iii) Electrolytic purification of aluminium.
Thus we can say that Option C is the correct answer.

Additional Information:
Some properties of Aluminium are:
A. Aluminium is a bluish white lustre metal.
B. The lustre is destroyed on long exposure to air due to formation of a thin film of oxide on the surface.
C. The density of aluminium is \[2.7\text{ }g\text{ }m{{L}^{-1}}\] (light metal).
D. It is malleable and ductile.
E. It is a good conductor of heat and electricity.
F. It melts at 660°C and boils at 1800°C.
G. It can be welded and cast but difficult to solder.

Note:
1. Aluminium is a very good reducing agent and reduces oxides of metals like Cr, Fe, Mn, etc.
\[C{{r}_{2}}{{O}_{3}}+2Al\xrightarrow{{}}2Cr+A{{l}_{2}}{{O}_{3}}+heat\]
\[F{{e}_{2}}{{O}_{3}}+2Al\xrightarrow{{}}2Fe+A{{l}_{2}}{{O}_{3}}+heat\]
\[3M{{n}_{3}}{{O}_{4}}+8Al\xrightarrow{{}}9Mn+4A{{l}_{2}}{{O}_{3}}+heat\]

2. It reduces oxides of non-metals also.
\[3C{{O}_{2}}+4Al\xrightarrow{{}}2A{{l}_{2}}{{O}_{3}}+3C\]
\[3Si{{O}_{2}}+4Al\xrightarrow{{}}2A{{l}_{2}}{{O}_{3}}+3Si\]

3. Being more electropositive it displaces copper, zinc and lead from the solutions of their salts.
\[3ZnS{{O}_{4}}+2Al\xrightarrow{{}}A{{l}_{2}}{{(S{{O}_{4}})}_{3}}+3Zn\]
\[3CuS{{O}_{4}}+2Al\xrightarrow{{}}A{{l}_{2}}{{(S{{O}_{4}})}_{3}}+3Cu\]

Some uses of Aluminium are:
I. Aluminium being cheap and light metal is largely used for making household utensils, trays, frames, etc. Bodies of automobiles, aircraft and roofing are made of aluminium sheet.
II. Thin foils of Al are used in wrapping soaps, cigarettes and confectionery.
III. Al wire is used in transmission lines and coils for dynamos and motors.
IV. It is used for making silvery paints for covering iron and other materials.
V. It is used in the thermite process for the extraction of Cr, Mn, etc.
VI. Since it is not attacked by nitric acid, it is used in chemical plants and for transporting nitric acid.
VII. Because of its lightness, good conductivity and resistance to corrosion, it is used for making alloys which find applications in industries and arts.