Cost should not be the only and primary consideration in the selection of materials. The materials that have good properties like high strength /weight ratio must be selected, and cost can be a factor of selection among them later in the process. The quality of material must not be compromised due to cost.

The dimension of a material is a physical property. Dimension is the physical measurement of an object. Length, breadth and height describe the dimensions of an object. It is not an economic, technological or mechanical property.

Castability is a technological factor of materials. The ease with which the material can be cast is called castability. The higher the castability, easier the process. Melting point and availability are physical properties of a material.

A material that requires supplementary operations before being used in manufacturing is called supplementary operational requirement. The operations vary depending on the material. A few examples are plating, heat treatment etc. The materials cannot be used in their natural state. This is a disadvantage as it is more costly and time-consuming.

Porosity is the quantity of void space present in the structure of a material. It is the ratio of pore volume to the total structure volume. It is one of the physical properties of a material.

The availability of material is an economic consideration. The material being used for the construction of an aircraft must be available for all requirements. Structure and appearance are physical properties of a material.

Reliability of a material is important to maintain the quality of the material. The material has to be manufactured by a standard manufacturer that produces good quality material to ensure that the material is not easily damaged.

The above statement is incorrect. It is possible to recycle used copper goods by melting them and once again purifying them. The product that is obtained through this process can be used in making new commodities.

The amount of copper found in ores is different for different ores. There are also sulfide ores and oxide ores of copper. But, at the end of the extraction process, the copper obtained has a purity of around 99.9%.

Smelting is done to eradicate unwanted materials like sulfur and gangue minerals to the fullest extent possible. The output of the smelting phase is called copper matte. It is a combination of sulfur, copper and iron.

The above statement is correct. Oxide ores are typically processed using hydrometallurgy. Hydrometallurgy involves using water-based solutions to purify copper. This technique contains processes like solvent extraction etc.

Sulfide ores are usually processed through the technique known as pyrometallurgy. Pyrometallurgy involves several processes like froth flotation, thickening, smelting, electrolysis etc.

Copper is found in several ores. Some of the ores are chalcocite, cuprite, bornite, chalcopyrite etc. Magnesite and dolomite are not ores of copper, they are ores of the element magnesium.

The extraction of copper from its ores is done through several techniques that include roasting, refining, smelting, crushing etc. Dow's process is done to obtain the substance magnesium, not copper.

Crushing is one of the first things done in the extraction process of copper from its ore. Copper ore is crushed to a particular required size. Crushing is done to separate the particles to make it easier to obtain the pure material.

Copper is usually never found in a natural state. Copper is found in several ores across the world including sulfide ore which contains 0.5 "“ 2% of copper. It has to undergo several processes to attain purity.