[2 Mark Question Answer]

Question 12 Marks

Name the probable cation present.
(a) Reddish brown precipitate insoluble in sodium hydroxide.
(b) Gelatinous white precipitate soluble in excess of ammonium hydroxide.

Answer

(a) Fe³⁺
(b) Zn²⁺

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Question 22 Marks

State giving observations.
(a) What happens when calcium carbonate reacts with dilute HCl?
(b) What happens when we add ammonium hydroxide to calcium salts, explain?

Answer

(a) Brisk effervescence of carbon dioxide is seen.
CaCO₃ + 2HCl(dil.) → CaCl₂ + H₂O + CO₂
(b) No precipitate is seen, as ammonium hydroxide has low concentration of hydroxide ions as it is a weak base.

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Question 32 Marks

(a) Define Amphoteric oxide.
(b) Write atleast one example of Amphoteric oxide and also state the chemical equations involved.

Answer

(a) The metal oxides that react with both acid and alkalies to form salt and water.
(b) ZnO + 2HCl → ZnCl₂ + H₂O
ZnO + 2NaOH → Na₂ZnO₂ + H₂O

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Question 42 Marks

State the observations.
(i) Copper sulphate crystals when heated in excess.
(ii) What happens when excess of sodium hydroxide is added to copper sulphate solution?

Answer

(i) It loses its water of crystallization and turns colourless.
$\underset{\text { Blue }}{ CuSO _4 \cdot 5 H _2 O ( s )} \xrightarrow{\Delta} \underset{\text { Colourless }}{ CuSO _4(s)}+5 H _2 O ( g )$
(ii) It turns pale blue in colour insoluble in excess of NaOH.
$CuSO _4( aq )+2 NaOH ( aq ) \longrightarrow Na _2 SO _4( aq )+ Cu ( OH )_2(s)$

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Chemistry [2 Mark Question Answer]

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