JEE Main 2022 · 24 June · evening · Numerical answer · +4 / −0
(a) Baryte, (b) Galena, (c) Zinc blende and (d) Copper pyrites. How many of these minerals are sulphide based?
Answer and solution
Answer 3
Solution
Chemistry ma’am · 2 steps
Write the formula of each ore and look at the anion: only one of the four is a sulphate, not a sulphide.
- What to check. A sulphide ore has the metal joined to S²⁻ ions. A sulphate ore has SO₄²⁻ ions instead, so containing sulphur is not enough.
Mineral Formula Anion Sulphide? Baryte BaSO₄ SO₄²⁻ No, it is a sulphate Galena PbS S²⁻ Yes Zinc blende ZnS S²⁻ Yes Copper pyrites CuFeS₂ S²⁻ Yes - So. Galena, zinc blende and copper pyrites are sulphide ores, while baryte is a sulphate. The count is 3.
The common slip: 4. Counting baryte as a sulphide because its formula has sulphur gives 4. Baryte is BaSO₄, a sulphate.
The idea to keep. Sulphur in a formula does not make it a sulphide. Look for bare S²⁻, not SO₄²⁻. Galena, zinc blende, cinnabar and the pyrites are the sulphide ores to remember.
Answer from the NTA final answer key. Solution by PrepWiser.