36 + Interview Questions in Mineral Acids in Corrosion Engineering Page 1 InterviewSolution

1.	What are the principal applications of Duriron?(a) Cast forms of pumps, valves, heat exchangers for chemical plant(b) In manufacturing and handling of nitric acid(c) In the ammonia oxidation process(d) Cast forms of pumps, valves, heat exchangers for chemical plant, in manufacturing and handling of nitric acid and ammonia oxidation processI got this question in homework.My doubt is from Mineral Acids in section Mineral Acids of Corrosion Engineering
Answer» The correct ANSWER is (d) Cast forms of pumps, VALVES, heat exchangers for chemical plant, in MANUFACTURING and handling of nitric acid and ammonia oxidation PROCESS Explanation: Principal applications of DURIRON are: i. Cast forms of pumps, valves, heat exchangers for chemical plants ii. In manufacturing and handling of nitric acid iii. In the ammonia oxidation process.

Discussion

2.	Which of the following acid is produced relatively higher than other acids?(a) Nitric acid(b) Sulfuric acid(c) Phosphoric acid(d) Hydrofluoric acidThis question was addressed to me during an online exam.This question is from Mineral Acids topic in chapter Mineral Acids of Corrosion Engineering
Answer» Correct option is (b) Sulfuric acid Easy explanation: Sulfuric acid is PRODUCED RELATIVELY higher than other acids. The chemical formula for sulfuric acid is H2SO4. It is produced by absorbing WATER into OLEUM.

Discussion

3.	Which of the following is/are the class2 corrosion-resistant materials in nitric acid?(a) Aluminum and Stainless steels(b) Aluminum, Hastelloy, and Inconel(c) Hastelloy and Inconel(d) Hastelloy and TitaniumThe question was posed to me in examination.Query is from Mineral Acids topic in portion Mineral Acids of Corrosion Engineering
Answer» The correct option is (b) Aluminum, Hastelloy, and Inconel The best EXPLANATION: CLASS2 corrosive resistance materials of nitric acid are the materials that are used in only certain specific CONDITIONS of TEMPERATURE and concentration because of limited corrosion resistance and cost. This includes Aluminum, Hastelloy, and Inconel.

Discussion

4.	Which of the following metal is used for hydrochloric acid to avoid contamination?(a) Titanium(b) Tantalum(c) Molybdenum(d) CupronickelsThe question was posed to me in an internship interview.I'd like to ask this question from Mineral Acids in section Mineral Acids of Corrosion Engineering
Answer» Right choice is (b) Tantalum The BEST explanation: Hydrochloric acid is the most difficult of the COMMON acids to handle REGARDING corrosion. Tantalum is an EXPENSIVE METAL but it is often used to avoid contamination.

Discussion

5.	Which of the following concentration of sulfuric acid in which the corrosion rate of steel is minimum?(a) Less than 30%(b) Greater than 70%(c) 30% – 70%(d) above 110%I have been asked this question in a job interview.The origin of the question is Mineral Acids topic in chapter Mineral Acids of Corrosion Engineering
Answer» Correct CHOICE is (b) Greater than 70% To explain: Ordinary steels are widely USED for various concentrations of SULFURIC acid greater than 70% purity. Dilute acids attack STEEL very RAPIDLY and result in faster degradation.

Discussion

6.	Which of the following materials exhibits poor corrosion resistance to phosphoric acid?(a) Aluminum and brass(b) Aluminum, brass, steel, cast iron, ferritic and martensitic stainless steels(c) Steel and cast iron(d) Ferritic and martensitic stainless steelsThis question was posed to me in examination.I want to ask this question from Mineral Acids in division Mineral Acids of Corrosion Engineering
Answer» Correct choice is (B) Aluminum, brass, STEEL, cast iron, ferritic and martensitic stainless STEELS Easiest explanation: Metals such as aluminum, brass, steel, cast iron, ferritic, and martensitic stainless steels exhibit poor corrosion RESISTANCE to phosphoric acid. Whereas 316 stainless steel and Durimet 20 are widely used for phosphoric acid.

Discussion

7.	Which of the following material is/are primarily used for hydrofluoric acid?(a) High-silicon cast iron(b) Magnesium(c) Aluminum(d) Glass and stonewareThe question was asked by my college director while I was bunking the class.Question is taken from Mineral Acids in section Mineral Acids of Corrosion Engineering
Answer» Correct answer is (B) Magnesium Easy EXPLANATION: Materials such as high-silicon cast iron, ALUMINUM, GLASS, and stoneware are generally resistant to many acids but these are readily attacked in hydrofluoric acid. WHEREAS magnesium is practically immune to corrosion because of the formation of a surface fluoride film.

Discussion

8.	Which of the following is/are the factors that affect the corrosion resistance of steel in concentrated sulfuric acid?(a) High velocity(b) Temperature of acid(c) Aeration(d) High velocity, temperature, and aerationThis question was posed to me in an international level competition.My question comes from Mineral Acids topic in chapter Mineral Acids of Corrosion Engineering
Answer» The correct answer is (d) High velocity, temperature, and aeration Explanation: High velocity, the temperature of ACID and aeration are the FACTORS that affect the CORROSION resistance of steel in concentrated sulfuric acid (>70%).

Discussion

9.	Which of the following statements is/are true regarding the contact process?(a) Conversion of sulfur dioxide to sulfur trioxide takes place(b) Vanadium oxide is used as a catalyst(c) It accounts for 70% of the world’s production(d) Conversion of sulfur dioxide to sulfur trioxide takes place in the presence of vanadium catalyst and it accounts for 70% world’s productionI got this question by my college director while I was bunking the class.This key question is from Mineral Acids in section Mineral Acids of Corrosion Engineering
Answer» The correct choice is (d) Conversion of sulfur dioxide to sulfur trioxide takes PLACE in the presence of VANADIUM CATALYST and it accounts for 70% world’s production Easy EXPLANATION: Contact process: Sulfur compounds such as copper sulfide are burned to get SO2 Catalytic conversion of sulfur dioxide to sulfur trioxide takes place Absorption of SO3 into WATER produces sulfuric acid.

Discussion

10.	Which of the following metals will have a high influence on aeration and oxidizing agents in hydrochloric acid?(a) Copper and its alloys(b) Nickel and its alloys(c) Nickel-molybdenum alloys, copper, nickel and their alloys(d) Nickel-molybdenum alloysThis question was addressed to me at a job interview.My enquiry is from Mineral Acids topic in division Mineral Acids of Corrosion Engineering
Answer» Correct choice is (c) Nickel-molybdenum ALLOYS, copper, nickel and their alloys To ELABORATE: Nickel-molybdenum alloys, copper, nickel, and their alloys will have a high influence on aeration and oxidizing agents in HYDROCHLORIC ACID. These materials show excellent corrosion resistance in reducing conditions but are rapidly attacked in oxidizing conditions.

Discussion

11.	Which of the following metal is suitable in handling high concentrations (>60%) of hydrofluoric acid?(a) Stainless steel(b) Brass(c) Steel(d) TitaniumI have been asked this question in examination.My question is from Mineral Acids in section Mineral Acids of Corrosion Engineering
Answer»

Discussion

12.	Hydrofluoric acid and fluorine are toxic and extreme care are mandatory in the handling of these materials.(a) True(b) FalseThis question was posed to me in an internship interview.My doubt stems from Mineral Acids in division Mineral Acids of Corrosion Engineering
Answer» RIGHT choice is (a) True The explanation: Hydrofluoric acid and fluorine are toxic and extreme care are mandatory in the handling of these materials. Metals such as MAGNESIUM are USED for some SHIPPING CONTAINERS because of the formation of a surface fluoride film.

Discussion

13.	Which of the following impurity in hydrochloric acid results in pitting corrosion?(a) Ferrous chloride(b) Ferric chloride(c) Potassium chloride(d) Sodium chlorideThis question was addressed to me during an interview for a job.The query is from Mineral Acids topic in section Mineral Acids of Corrosion Engineering
Answer» Correct option is (b) FERRIC chloride The explanation: Ferric chloride in small amounts is more destructive than OXYGEN in hydrochloric acid. It initiates pits and results in PITTING CORROSION on various METALS in the hydrochloric environment.

Discussion

14.	Which of the following is/are the class3 corrosion-resistant materials in nitric acid?(a) Copper and its alloys(b) Nickel and its alloys(c) Low-alloy steels(d) Low-alloy steels, copper, nickels and their alloysI got this question in final exam.The doubt is from Mineral Acids in portion Mineral Acids of Corrosion Engineering
Answer» Right OPTION is (d) Low-alloy steels, copper, nickels and their alloys For EXPLANATION I WOULD SAY: Class3 materials are recommended for use in a particular environment because of its less corrosion RESISTANCE. This includes copper and its alloys, nickel and its alloys and low-alloy steels.

Discussion

15.	Which of the following statements is/are true about titanium?(a) It has excellent corrosion resistance to fuming nitric acid(b) It is used as an oxidizer in fuel systems for rockets(c) It has excellent corrosion resistance to fuming nitric acid and it is used as an oxidizer in fuel systems for rockets(d) It doesn’t exhibit pyrophoric tendencies in red fuming nitric acidI had been asked this question in unit test.This intriguing question originated from Mineral Acids in portion Mineral Acids of Corrosion Engineering
Answer» CORRECT choice is (c) It has excellent CORROSION resistance to fuming nitric ACID and it is USED as an oxidizer in fuel systems for rockets Best explanation: Titanium has excellent corrosion resistance to fuming nitric acid and it is used as an oxidizer in fuel systems for rockets. Whereas it exhibits pyrophoric tendencies in red fuming nitric acid if the WATER content of the acid is below 1.5% and the nitrogen dioxide content is above 2.5%.

Discussion

16.	Which of the following is/are the impurities that cause corrosion in commercial phosphoric acid?(a) Fluorides(b) Chlorides(c) Sulfuric acids(d) Fluorides, chlorides and sulfuric acidThe question was asked in a job interview.I would like to ask this question from Mineral Acids in section Mineral Acids of Corrosion Engineering
Answer» Right OPTION is (d) Fluorides, CHLORIDES and sulfuric acid Easiest explanation: Corrosion by phosphoric acid depends on the methods of MANUFACTURING and impurities present in that COMMERCIAL acid. Impurities that are usually present in commercial phosphoric acid are fluorides, chlorides, and sulfuric acid.

Discussion

17.	Which of the following polymer has excellent corrosion resistance to nitric acid?(a) Teflon(b) Polyvinyl chloride(c) Polystyrene(d) PolyethyleneThis question was posed to me in class test.I need to ask this question from Mineral Acids in portion Mineral Acids of Corrosion Engineering
Answer» Correct option is (a) Teflon To EXPLAIN I would say: Teflon shows excellent CORROSION RESISTANCE to nitric acid. GLASS filled Teflon is widely used for rotating RINGS in mechanical seals for nitric acid pumps.

Discussion

18.	Which of the following is/are the examples of mineral acids?(a) Sulfuric acid and nitric acid(b) Hydrochloric acid and hydrofluoric acid(c) Sulfuric, nitric, hydrochloric, hydrofluoric and phosphoric acid(d) Sulfuric, nitric, hydrochloric and hydrofluoric acidThis question was posed to me in final exam.I would like to ask this question from Mineral Acids topic in section Mineral Acids of Corrosion Engineering
Answer» CORRECT answer is (c) Sulfuric, nitric, hydrochloric, hydrofluoric and PHOSPHORIC acid To EXPLAIN I would say: Mineral acid or INORGANIC acid is the acid derives from one or more inorganic COMPOUNDS on dissolution with water. This includes sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid, and phosphoric acid.

Discussion

19.	Why straight chromium stainless steels and austenitic stainless steels are not recommended for hydrofluoric acid applications?(a) Due to susceptibility to crevice(b) Due to limited corrosion resistance(c) Due to susceptibility to pitting(d) Sensitive to erosion-corrosionThe question was posed to me in a job interview.Question is taken from Mineral Acids in division Mineral Acids of Corrosion Engineering
Answer» The correct choice is (c) Due to susceptibility to pitting Explanation: Straight chromium STAINLESS steels and austenitic stainless steels are not recommended for HYDROFLUORIC acid applications due to their susceptibility to pitting CORROSION. Whereas (410) of stainless STEEL is sensitive to erosion-corrosion.

Discussion

20.	The corrosion resistance of Durichlor to nitric acid is better than that of Duriron.(a) True(b) FalseThis question was addressed to me by my college director while I was bunking the class.My question is taken from Mineral Acids in division Mineral Acids of Corrosion Engineering
Answer» RIGHT choice is (b) False For explanation: DURICHLOR is high-SILICON cast iron with 14.5% silicon and 3% MOLYBDENUM. It is not better corrosion resistant to nitric acid than that of Duriron. Because molybdenum doesn’t increase the corrosion resistance to nitric acid.

Discussion

21.	Which of the following metal is not corrosion resistant to sulfuric acid?(a) Grey cast iron(b) Duriron(c) Durimet 20(d) LeadI have been asked this question during an internship interview.My question is from Mineral Acids in section Mineral Acids of Corrosion Engineering
Answer» Correct choice is (a) Grey cast iron Best EXPLANATION: Grey cast iron is not corrosion resistant to SULFURIC ACID as it penetrates the METAL along with the graphite flakes. Though the corrosion RATES are small but the metal may split open in service.

Discussion

22.	Which of the following metal is an outstanding material that resists all concentrations of hydrofluoric acid at all temperatures?(a) Wrought Monel(b) Steel(c) Stainless steel(d) Hastelloy CThe question was posed to me in a national level competition.The question is from Mineral Acids topic in chapter Mineral Acids of Corrosion Engineering
Answer» Correct CHOICE is (a) WROUGHT Monel To explain: Wrought Monel is an outstanding metal in that it RESISTS all concentrations of hydrofluoric acid at all temperatures including BOILING. Monel is the best selection of material for hydrofluoric environment APPLICATIONS.

Discussion

23.	Which of the following materials is/are widely used for phosphoric acid?(a) 316 stainless steel(b) Durimet 20(c) Neither 316 stainless steel nor Durimet 20(d) Both 316 stainless steel and Durimet 20This question was posed to me in exam.I need to ask this question from Mineral Acids in section Mineral Acids of Corrosion Engineering
Answer» Right OPTION is (d) Both 316 stainless steel and DURIMET 20 Easy EXPLANATION: 316 stainless steel and Durimet 20 are the two alloys that are widely used for phosphoric acid. These alloys show the very little attack in concentrations up to 85% and TEMPERATURES including boiling.

Discussion

24.	Which of the following is/are the class1 corrosion resistance materials in hydrochloric acid?(a) Chlorimet 2 and Chlorimet 3(b) Hastelloy B and C(c) Zirconium and molybdenum(d) Chlorimet 2 and 3, Hastelloy B and C, Zirconium, Molybdenum and TantalumThe question was posed to me by my college director while I was bunking the class.Origin of the question is Mineral Acids in division Mineral Acids of Corrosion Engineering
Answer» The correct option is (d) Chlorimet 2 and 3, Hastelloy B and C, Zirconium, Molybdenum and Tantalum To explain I would SAY: Class1 materials are the materials that are used for a particular environment and it is generally recommended for a VARIETY of CONDITIONS of TEMPERATURE and concentration. Class1 materials for hydrochloric acid include Chlorimet 2 and 3, Hastelloy B and C, Zirconium, Molybdenum, and Tantalum.

Discussion

25.	Duriron has better corrosion resistance than Durichlor in hydrochloric acid.(a) False(b) TrueThis question was posed to me by my school principal while I was bunking the class.Question is from Mineral Acids topic in chapter Mineral Acids of Corrosion Engineering
Answer» RIGHT answer is (a) False To EXPLAIN: DURICHLOR is high-silicon cast iron with 14.5% silicon and 3% molybdenum is more CORROSION resistant than Duriron in hydrochloric acid.

Discussion

26.	Which of the following alloying elements are not recommended in the sulfuric acid environment?(a) Chromium(b) Nickel(c) Molybdenum(d) Nickel and molybdenumThe question was posed to me in examination.This interesting question is from Mineral Acids topic in division Mineral Acids of Corrosion Engineering
Answer» Right ANSWER is (c) Molybdenum The explanation: Alloying elements are ADDED in base metal to exhibit certain specific properties such as corrosion RESISTANCE, thermal properties, or mechanical properties. Here molybdenum is not recommended as an alloying element in high-silicon cast IRON for sulfuric acid application.

Discussion

27.	Which of the following method is used to produce sulfuric acid?(a) Contact process(b) Ostwald process(c) Solvay process(d) Haber processI had been asked this question in class test.Asked question is from Mineral Acids topic in section Mineral Acids of Corrosion Engineering
Answer» Correct OPTION is (a) CONTACT process The EXPLANATION is: Sulfuric acid is produced by the contact process or LEADS chamber process. It is produced by absorbing SO3 with water. This process accounts for 70% of WORLD production.

Discussion

28.	Duriron exhibits excellent corrosion resistance in concentrations over 45% at temperatures including boiling.(a) True(b) FalseI got this question in final exam.Origin of the question is Mineral Acids in section Mineral Acids of Corrosion Engineering
Answer» Right choice is (a) True The explanation is: Duriron is high-silicon cast iron with 14.5% silicon EXHIBITS excellent corrosion resistance in CONCENTRATIONS over 45% at temperatures including boiling. It is a class1 material in the usage of nitric acid.

Discussion

29.	Which of the following steels will have less corrosion rate in boiling 65% nitric acid?(a) 4.5% chromium steel(b) 8% chromium and 8% nickel steel(c) 18% chromium and 8% nickel stainless steel(d) 18% chromium stainless steelI have been asked this question in examination.The above asked question is from Mineral Acids topic in portion Mineral Acids of Corrosion Engineering
Answer»

Discussion

30.	Which of the following is/are the applications of Duriron because of its corrosion resistance and inherent hardness?(a) To manufacture pumps, valves, and fans(b) To make heat exchangers(c) Impressed–current anodes(d) To manufacture pumps, valves, fans, heat exchangers and impressed-current anodesThis question was posed to me in unit test.Question is from Mineral Acids topic in section Mineral Acids of Corrosion Engineering
Answer» Correct answer is (d) To MANUFACTURE pumps, valves, fans, HEAT EXCHANGERS and impressed-current anodes The best I can explain: Duriron is high-silicon cast iron with high corrosion resistance and INHERENT hardness. It is USED to manufacture pumps, valves, fans, heat exchangers, and impressed-current anodes.

Discussion

31.	Which of the following is/are the class2 corrosion resistance materials in hydrochloric acid?(a) Bronzes and Cupronickels(b) Hastelloy D and Duriron(c) Bronzes, Stainless steels, Bronzes, Cupronickels, Hastelloy D and Duriron(d) Stainless steels and DurironI got this question in an internship interview.My doubt stems from Mineral Acids topic in section Mineral Acids of Corrosion Engineering
Answer» The CORRECT CHOICE is (c) Bronzes, Stainless steels, Bronzes, Cupronickels, Hastelloy D and Duriron To explain: CLASS2 corrosive RESISTANCE MATERIALS of nitric acid are the materials that are used in only certain specific conditions of temperature and concentration because of limited corrosion resistance and cost. This includes bronzes, stainless steels, bronzes, cupronickels, Hastelloy D, and Duriron.

Discussion

32.	Lead is used extensively for sulfuric acid in the lower concentration ranges (
Answer» Correct answer is (B) True The explanation is: LEAD is USED extensively for sulfuric acid in the lower concentration ranges (<70%). It is not recommended above 70% purity is DUE to the SOLUBILITY of lead sulfate surface film in the acid.

Discussion

33.	Which of the following is/are the impurities in commercial hydrofluoric acid that decreases corrosion of steel?(a) Sulfuric acid(b) Fluosilicic acid(c) Neither sulfuric acid nor fluosilicic acid(d) Both sulfuric acid and fluosilicic acidI had been asked this question in quiz.My query is from Mineral Acids in division Mineral Acids of Corrosion Engineering
Answer» RIGHT answer is (d) Both sulfuric acid and fluosilicic acid To explain: USUALLY IMPURITIES such as sulphuric acid and fluosilicic acid are PRESENT in commercial hydrofluoric acid that reduces the corrosion of STEEL.

Discussion

34.	Which of the following is/are the class1 corrosion resistance materials in nitric acid?(a) High-silicon cast irons(b) Stainless steels (type 430)(c) Titanium(d) High-silicon cast iron, stainless steels, and titaniumI have been asked this question in an interview for internship.I'm obligated to ask this question of Mineral Acids topic in division Mineral Acids of Corrosion Engineering
Answer» Right ANSWER is (d) High-silicon cast iron, stainless steels, and titanium The explanation is: Class1 materials are the materials that are USED for a particular ENVIRONMENT and it is generally recommended for a VARIETY of conditions of temperature and concentration. Class1 materials for NITRIC acid includes high-silicon cast irons, stainless steels, and titanium.

Discussion

35.	Which of the following non-metallic has the highest corrosive resistance to the phosphoric acid with temperature?(a) Teflon(b) Graphite(c) Polyvinyl chloride(d) PolyethyleneThe question was asked by my college professor while I was bunking the class.This interesting question is from Mineral Acids topic in portion Mineral Acids of Corrosion Engineering
Answer» Right ANSWER is (a) Teflon Easy explanation: Teflon is a non-metallic material that has the highest corrosion RESISTANCE to phosphoric ACID up to 550°C. Teflon is ALSO known as polytetrafluoroethylene (CF2=CF2).

Discussion

36.	What are the principal uses of sulfuric acid?(a) Production of hydrochloric acid(b) Manufacturing of dyes, fertilizers, and drugs(c) Pickling of steels and other metals(d) Production of hydrochloric acid, manufacturing of dyes, fertilizers and drugs and pickling of steelsThe question was posed to me by my college professor while I was bunking the class.My enquiry is from Mineral Acids in section Mineral Acids of Corrosion Engineering
Answer» Right CHOICE is (d) Production of hydrochloric ACID, manufacturing of dyes, fertilizers and drugs and pickling of STEELS Explanation: Principle uses of sulfuric acid are: Production of hydrochloric acid and other chemicals Manufacturing of dyes, fertilizers, drugs, EXPLOSIVES, and rayon Pickling of steels and other metals Laboratory USAGE.

Discussion

Explore topic-wise InterviewSolutions in .

Which of the following acid is produced relatively higher than other acids?(a) Nitric acid(b) Sulfuric acid(c) Phosphoric acid(d) Hydrofluoric acidThis question was addressed to me during an online exam.This question is from Mineral Acids topic in chapter Mineral Acids of Corrosion Engineering

Which of the following metal is used for hydrochloric acid to avoid contamination?(a) Titanium(b) Tantalum(c) Molybdenum(d) CupronickelsThe question was posed to me in an internship interview.I'd like to ask this question from Mineral Acids in section Mineral Acids of Corrosion Engineering

Which of the following metal is suitable in handling high concentrations (>60%) of hydrofluoric acid?(a) Stainless steel(b) Brass(c) Steel(d) TitaniumI have been asked this question in examination.My question is from Mineral Acids in section Mineral Acids of Corrosion Engineering

Hydrofluoric acid and fluorine are toxic and extreme care are mandatory in the handling of these materials.(a) True(b) FalseThis question was posed to me in an internship interview.My doubt stems from Mineral Acids in division Mineral Acids of Corrosion Engineering

Which of the following polymer has excellent corrosion resistance to nitric acid?(a) Teflon(b) Polyvinyl chloride(c) Polystyrene(d) PolyethyleneThis question was posed to me in class test.I need to ask this question from Mineral Acids in portion Mineral Acids of Corrosion Engineering

The corrosion resistance of Durichlor to nitric acid is better than that of Duriron.(a) True(b) FalseThis question was addressed to me by my college director while I was bunking the class.My question is taken from Mineral Acids in division Mineral Acids of Corrosion Engineering

Which of the following metal is not corrosion resistant to sulfuric acid?(a) Grey cast iron(b) Duriron(c) Durimet 20(d) LeadI have been asked this question during an internship interview.My question is from Mineral Acids in section Mineral Acids of Corrosion Engineering

Duriron has better corrosion resistance than Durichlor in hydrochloric acid.(a) False(b) TrueThis question was posed to me by my school principal while I was bunking the class.Question is from Mineral Acids topic in chapter Mineral Acids of Corrosion Engineering

Which of the following method is used to produce sulfuric acid?(a) Contact process(b) Ostwald process(c) Solvay process(d) Haber processI had been asked this question in class test.Asked question is from Mineral Acids topic in section Mineral Acids of Corrosion Engineering

Duriron exhibits excellent corrosion resistance in concentrations over 45% at temperatures including boiling.(a) True(b) FalseI got this question in final exam.Origin of the question is Mineral Acids in section Mineral Acids of Corrosion Engineering

Lead is used extensively for sulfuric acid in the lower concentration ranges (