Which of the following is a method of concentration of sulphide ores?
A. Froth flotation
B. Smelting
C. Magnetic separation
D. Calcination
Answer: Option A
Solution (By JKExamLibrary)
Froth flotation is used for sulphide ores (ZnS, PbS, CuFeS₂). Ore particles adhere to oil froth and float, gangue sinks. Magnetic separation for magnetic ores. Calcination and smelting are extraction steps, not concentration.
Explanation:
The object to be plated is connected to the negative terminal (cathode). Metal ions from the electrolyte are reduced and deposited on the cathode. The anode is usually the plating metal, which dissolves to replenish the electrolyte. For example, in silver plating, the article is the cathode and silver bar is the anode.
Assertion (A): A catalyst does not change the equilibrium yield of a reaction. Reason (R): A catalyst speeds up both the forward and backward reactions equally.
A.A is true but R is false.
B.A is false but R is true.
C.Both A and R are true and R is the correct explanation of A.
D.Both A and R are true but R is NOT the correct explanation of A.
Explanation:
A catalyst lowers the activation energy for both the forward and reverse reactions by the same amount. Therefore, it increases the rates of both reactions equally, allowing the system to reach equilibrium faster, but without changing the final equilibrium concentrations (yield). Both statements are correct and R explains A.
Explanation:
Cobalt-60 is a gamma-ray emitter used in radiotherapy to destroy cancerous cells. Iodine-131 is used for thyroid cancer and disorders. Carbon-14 is used in radiocarbon dating. Uranium-235 is used as fuel in nuclear reactors and weapons. Radioisotopes for medical use are produced in nuclear reactors. Gamma rays penetrate and damage DNA of rapidly dividing cells.
No comments yet. Be the first to start the discussion!