Chemistry
Select the odd one out and justify your answer.
(a) Zn, Fe, Mg and Na
(b) SO2, H2S, NH3 and CO2
(c) Fe, Zn, Cu and Mg
(d) Fe, Pb, Al and Zn
Hydrogen
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Answer
(a) Na, as it reacts with cold water to produce hydrogen gas while others react with hot water/steam to produce hydrogen gas.
(b) NH3, as it is basic in nature but rest are acidic.
(c) Cu, as it is below hydrogen in the metal activity series, hence it cannot displace hydrogen from dilute acids whereas others are above hydrogen and can displace it from dilute acids.
(d) Fe as rest of the elements Pb, Al and Zn have unique nature. They can react with acids as well as hot concentrated alkalis to form hydrogen and a soluble salt.
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Related Questions
Divide the following redox reactions into oxidation and reduction half reactions.
(i) Zn + Pb2+ ⟶ Zn2+ + Pb
(ii) Zn + Cu2+ ⟶ Zn2+ + Cu
(iii) Cl2 + 2Br- ⟶ Br2 + 2Cl-
(a) Write the equation in the ionic form
CuSO4 (aq) + Fe (s) ⟶ FeSO4 (aq) + Cu (s)
(b) Divide the above equation into oxidation and reduction half reactions.
Give reasons
(a) Hydrogen is collected by the downward displacement of water and not of air, even though it is lighter than air.
(b) A candle brought near the mouth of a jar containing hydrogen gas starts burning but is extinguished when pushed inside the jar.
(c) Apparatus for laboratory preparation of hydrogen should be airtight and away from a naked flame.
Write half-reactions for the following reaction :
A+ + B ⟶ A + B+ and name the following:
(a) oxidizing agent
(b) substance oxidized
(c) reducing agent.