BaCl₂ + Na₂SO₄ → BaSO₄↓ + 2NaCl is best classified as:
A. Combination
B. Decomposition
C. Displacement
D. Double displacement (precipitation)
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Correct option: D — Double displacement (precipitation)
Ions exchange partners and BaSO₄ comes out as a precipitate.
Q.2Long answerhardImportantOxidation and reduction
How can you tell oxidation and reduction in terms of oxygen, hydrogen and electrons? Use 2H₂S + SO₂ → 3S + 2H₂O as an example.
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Oxidation: gain of oxygen / loss of hydrogen / loss of electrons.
Reduction: loss of oxygen / gain of hydrogen / gain of electrons.
In 2H₂S + SO₂ → 3S + 2H₂O, H₂S loses hydrogen (oxidised) and SO₂ loses oxygen (reduced). Electrons move from sulphur in H₂S toward sulphur in SO₂.
Name the oxidising agent (the one that gets reduced) in the last line.
These practice sets use original GKSchools wording — they are not a verbatim dump of the NCERT textbook. “Important” means high-weight practice for the chapter, not a claim that these are previous-year exam questions.