Occurrence of Metals in Nature Ores and Minerals - UNSOLVED PRACTICE SET

Q7. Differentiate between a mineral and an ore. Give one example of each.

Q8. Name the ores of the following metals: (i) Iron, (ii) Aluminium, (iii) Zinc, (iv) Copper.

Q9. Your grandfather shows you a shiny rock he found near a river and claims it is gold ore. How would you explain to him the difference between a mineral, an ore, and native metal? Why is gold often found in native state?

Q10. Why are highly reactive metals like sodium and potassium not found in nature in the free state? Explain with reference to their reactivity.

Q11. What is gangue? How is it removed from the ore during the extraction of metals?

Q12. Write the chemical formulae of the following ores: (i) Haematite, (ii) Bauxite, (iii) Zinc blende, (iv) Copper pyrites.

Q13. Define minerals and ores. Explain the difference between them with examples. Describe why some metals are found in native state while others are found in combined state. Name the ores of iron, aluminium, copper, and zinc, and write their chemical formulae. What is the role of gangue in ore processing?

Q14. A student is given four rock samples and told that they contain metals:

Sample A: Contains Fe₂O₃ with 60% iron content

Sample B: Contains Al₂O₃·2H₂O with 30% aluminium content

Sample C: Contains CuFeS₂ with 25% copper content

Sample D: Contains small amounts of gold particles mixed with sand

(a) Identify which samples are minerals and which are ores.

(b) For each metal, name the common ore found in India.

(c) Explain why Sample D can be processed by physical methods while Sample A requires chemical processing.

(d) What is the gangue in Sample A, and how is it removed?

(e) Why is Sample B considered an ore of aluminium even though it has a lower metal content than Sample A has iron?

Q15. "India is rich in mineral resources, but the distribution is uneven, and sustainable mining is a major challenge." Discuss this statement by explaining: (i) the major iron ore deposits in Odisha and Jharkhand, (ii) the bauxite deposits in Odisha and Gujarat, (iii) the environmental impact of mining, and (iv) why India still imports some metals despite having domestic ore deposits.

Q16. A mining company analyses the composition of an iron ore sample:

Table

Component Mass (kg)

Fe₂O₃ 800

SiO₂ (gangue) 150

Other impurities 50

(a) Calculate the total mass of the ore sample.

(b) Calculate the percentage of Fe₂O₃ in the ore.

(c) Calculate the mass of iron present in the Fe₂O₃. (Molar masses: Fe₂O₃ = 160 g/mol, Fe = 56 g/mol)

(d) If the company processes 1000 tonnes of this ore daily, calculate the mass of iron obtained per day.

(e) If the extraction process is 80% efficient, calculate the actual mass of iron obtained daily.

Q17. India is a major producer of bauxite, the ore of aluminium.

(a) Bauxite contains Al₂O₃·2H₂O. If a sample contains 60% Al₂O₃·2H₂O, calculate the mass of pure Al₂O₃ in 500 kg of bauxite. (Molar masses: Al₂O₃·2H₂O = 156 g/mol, Al₂O₃ = 102 g/mol)

(b) Calculate the mass of aluminium that can be extracted from this Al₂O₃. (Atomic mass of Al = 27)

(c) If India produces 20 million tonnes of bauxite annually, and the average aluminium content is 25%, calculate the potential aluminium production.

(d) Why is only about 30% of India's bauxite converted to aluminium? What factors limit production?

(e) The Balco (Bharat Aluminium Company) plant in Chhattisgarh is a major aluminium producer. Why are aluminium plants located near bauxite mines or power stations?

Q18. A geological survey team discovers a new mineral deposit in Rajasthan.

(a) The team finds a rock containing ZnS (zinc blende). If the rock contains 40% ZnS, calculate the mass of zinc in 1000 kg of rock. (Molar masses: ZnS = 97 g/mol, Zn = 65 g/mol)

(b) The team also finds traces of native silver. Why is silver found in native state in some locations but as compounds in others?

(c) If the deposit contains 0.1% silver by mass, calculate the mass of silver in 10,000 tonnes of ore.

(d) The Zawar mines in Rajasthan are famous for zinc extraction. Why is the concentration of ore necessary before extraction?

(e) If the concentration process increases the ZnS content from 40% to 80%, calculate the mass of concentrated ore obtained from 1000 kg of raw ore.