Chemistry · Science General

Metallurgical Processes

1,436 Questions

This section explores key metallurgical processes including ore concentration, pyrometallurgy, and metal refining. It also covers corrosion and the properties of refractory materials. These chemistry questions are relevant for engineering and science entrance tests.

Pyrometallurgy furnacesMetal refining techniquesCorrosion protection methodsOre concentrationAuto reduction process

Metallurgical Processes Questions

Multiple choice

On dipping Zn rod in NaCl solution, the portion dipped in solution gets corroded while portion above water is protected. This type of corrosion is called

  1. inter-granular corrosion

  2. crevice corrosion

  3. waterline corrosion

  4. differential aeration corrosion
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

If a metal rod is dipped in electrolyte, the portion dipped in water is poor in oxygen concentration and works as anode and gets corroded and the portion above the water acts as cathode, which gets protected. The system will act as a concentration cell. This type of corrosion is called differential aeration corrosion.

Multiple choice

Which of the following statements is false?

  1. Chemical formula of rust is Fe2O3.xH2O.

  2. Pitting corrosion occurs due to breaking of oxide layer of the metal.

  3. Anodic coating protects underlying metal due to higher reduction potential.

  4. Galvanized iron is not used in making cooking utensils.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Anodic coating protects underlying metal due to higher oxidation potential.

Multiple choice

Which of the following statements is incorrect regarding galvanic series?

  1. It predicts the corrosive tendencies of metals and alloys.

  2. Standard hydrogen electrode is used as a reference electrode.

  3. Positioning of metals and alloys can change.

  4. Oxidation potential of metals is arranged in decreasing order of activity of a series of metal.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Calomel electrode is used as a reference electrode for devising galvanic series.

Multiple choice

____ is based on the phenomenon of electrolysis.

  1. Electrolytic refining

  2. Liquation

  3. Distillation

  4. Poling
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The refining of a metal (such as copper) by electrolysis, in which the crude metal used as the anode goes into solution and the pure metal is deposited upon the cathode is called electrolytic refining.

Multiple choice

_____ is a method used for purification of germanium.

  1. Van Arkel method

  2. Zone refining

  3. Electrolytic refining

  4. Liquation
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Zone melting (or zone refining or floating zone process) is a group of similar methods of purifying crystals, in which a narrow region of a crystal is molten, and this molten zone is moved along the crystal (in practice, the crystal is pulled through the heater). The molten region melts impure solid at its forward edge and leaves a wake of purer material solidified behind it as it moves through the ingot. The impurities concentrate in the melt, and are moved to one end of the ingot.

Multiple choice

____ is a method in which a barrier film is introduced between iron and atmospheric oxygen and moisture.

  1. Barrier protection

  2. Sacrificial protection

  3. Anti-rust use

  4. Polishing
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

 Barrier protection is the oldest and most widely used method of corrosion protection. It acts by isolating the base metal from the environment. Like paints, the hot-dip galvanized coating provides barrier protection. A barrier film is introduced between iron and atmospheric oxygen and moisture.

Multiple choice

__________ can be purified by liquation method.

  1. Tin and lead

  2. Copper and silver

  3. Gold and zinc

  4. Nickel and chromium
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This process is used for refining easily fusible metals like lead and tin. The impure metal is heated on the sloppy hearth of an electric furnace. The metal melts and flows down, leaving the impurities.

Multiple choice

In which of the following cases will the extent of corrosion be enhanced?

  1. If the metal is highly unreactive

  2. In the absence of carbon dioxide

  3. If impurities are present in the metal

  4. If the metal is coated with a layer of protective coating
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The corrosion will be enhanced: (a)  if impurities are present in the metal (b)  in the presence of carbon dioxide (c)  if the metal is highly reactive  

Multiple choice

The rate and extent of corrosion do not depend upon

  1. position in galvanic series

  2. relative areas of anodic and cathodic parts

  3. position in electrochemical series

  4. purity of metal
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This option is correct because electrochemical series does not provide a generalization to the rate of corrosion of elements as per their position in electrochemical series. For example: In Zn-Al couple, zinc is corroded and Al behaves as cathodic part. However, Al is above Zn in electrochemical series, which is due to the fact that Al develops strongly adhering oxide layer on its surface, thereby making effective electrode potential more positive.

Multiple choice

S in the crude oil can be removed by treating with

  1. iron oxide

  2. copper oxide

  3. zinc oxide

  4. magnesium oxide
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sulfur in crude oil is commonly removed using copper oxide through processes like copper sweetening. The copper oxide reacts with sulfur compounds to form copper sulfide, effectively removing sulfur impurities. Iron oxide, zinc oxide, and magnesium oxide are not typically used for this specific desulfurization purpose.

Multiple choice

Door locks are made of metals because metals

  1. have lustre

  2. are opaque

  3. are insoluble in water

  4. are hard and strong

  5. are naturally available
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Yes, due to the hardness and the strength of the metals, door locks are made up of metals.

Multiple choice

Why does 1 kg of iron occupy less space as compared to 1 kg sponge?

  1. Iron has less density than sponge.

  2. Iron has more density than sponge.

  3. Iron is hard but sponge is soft.

  4. Iron has magnetic property but sponge has not.

  5. Iron has lustre but sponge has not.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Yes, the density of the iron is more than sponge, due to this 1 kg iron occupies less space but sponge occupies more space.