Match the basic radicals listed in column-I with the properties listed in column-II.
Column-I | Column-II | ||
(Basic radical) | (Properties) | ||
(a) | Mn2+ | (p) | Forms coloured metaborate in oxidising flame in borax bead test. |
(b) | Cr3+ | (q) | Forms white precipitate with sodium hydroxide but on exposure to air turns rapidly brown. |
(c) | Al3+ | (r) | With both potassium cyanide (not in excess) and ammonia solution separately forms reddish brown precipitate. |
(d) | Fe3+ | (s) | With excess of sodium hydroxide forms soluble complex but on adding acid to soluble complex, a precipitate is obtained which redissolves on adding excess of acid. |
Text Solution
Verified by ExpertsA
(A - p,q ; B - p,s ; C - s ; D - p,r)
Sol. Mn 2+ meta borate 
Amethyst red
Mn 2+ + 2OH – 
Mn(OH) 2 ↓ (white)
Mn(OH) 2 ↓ (white) + O 2 (air) 
2MnO(OH 2 ) ↓ (brown)
Cr 3+ metaborate 
Green
Cr 3+ + 3OH – 
Cr(OH) 3 ↓ (green)
Cr(OH) 3 + OH – 
[Cr(OH) 4 ] – (green coloured soluble complex).
[Cr(OH) 4 ] – + H + 
Cr(OH) 3 ↓ + H 2 O
Cr(OH) 3 ↓ + 3H + ↓ 
Cr 3+ + 3H 2 O
Al 3 + 3OH – 
Al(OH) 3 ↓ (white)
Al(OH) 3 + OH – 
[Al(OH) 4 ] – (colourless soluble complex).
[Al(OH) 4 ] – + H + 
Al(OH) 3 ↓ + H 2 O
Al(OH) 3 + 3H + ↓ 
Al 3+ + 3H 2 O
Fe 3+ metaborate 
Pale yellow
Fe 3+ + 3CN – 
Fe(CN) 3 ↓ (reddish brown)
Fe(CN) 3 ↓ + 3CN – 
Fe(CN) 6 ] 3– (yellow colour soluble complex).
Fe 3+ + 3OH – Fe(OH) 3 ↓ (reddish brown).
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