Question

Duralumin is an alloy. It does not contains:
A. Al.
B. Cu.
C. Mg.
D. Na.

Answer 1

Hint: In order to solve this problem, we must note that aluminum metal is light but not strong, but its alloy with copper, magnesium and manganese called duralumin is both light and strong.

Complete step-by-step answer:
We know an alloy is a homogeneous mixture of two or more metals, or a metal and small quantities of non-metals).
An alloy is prepared by combining the different metals in the necessary proportions in molten state, and then cooling their mixture at room temperature.
Duralumin is a trade name for one of the earliest types of aluminum alloys that are hardy to age. In addition to aluminium , copper, manganese and magnesium are the major materials in duralumin.
Duralumin is a special type of metal, which is rendered solid by heat treatment. It can be pounded, polished, riveted, welded, or machined well. The duralumin, which is effectively treated with heat, can be corrosion resistant. It can, and is ductile, carry heavy loads. This is especially suitable for the construction of an aircraft. Its strength improves as copper is applied to the alloy, but then it also makes it vulnerable to corrosion. The metallurgical bonding of the highly pure metal layer can increase the corrosion resistance for the duralumin sheet products. Such sheets are called alclad, and are widely used by the aviation industry.
Hence, we can say that duralumin contains copper (Cu), magnesium ( Mg) and manganese (Mn) but does not contain sodium (Na).
Therefore, the correct answer is choice (D).

Note: Duralumin alloy contains different compositions of aluminum , copper, manganese and magnesium, i.e. it consists of 90% aluminum, 4% copper, 1% magnesium and 0.5% to 1% manganese. It is an extremely tough alloy. For the screw machine goods it is used to make wire, bars and rods. It is used in places requiring good strength and good machinability.