Some Basic Concepts Of Chemistry Question 123

Question: When $ FeS _2 $ is burnt in air, it converts into $ Fe _2O _3. $ The change in percentage by weight of iron in the process is (Fe = 56)

Options:

A) 23% increase

B) 12% decrease

C) 12% increase

D) no change

Show Answer

Answer:

Correct Answer: A

Solution:

[a] $ \underset{Fe\frac{56}{120}\times 100=46.67}{\mathop{\underset{56+32\times 2=120}{\mathop{FeS _2}},}},\xrightarrow[{}]{{}}\underset{\frac{112}{160}\times 100,=,70}{\mathop{\underset{56\times 2+3\times 16,=160}{\mathop{Fe _2O _3}},}}, $ Percent increase = 70 – 46.67 = 23% (approx.)



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