HARD
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When dilute H2SO4 and H2O2 are added to a solution of chromate ions, an intense blue colour is produced, which is stable in ether. This is due to the formation of

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Important Questions on The d- and f-Block Elements

MEDIUM
Thermal decomposition of a Mn compound X at 513 K results in compound Y, MnO2 and a gaseous product. MnO2 reacts with NaCl and concentrated H2SO4 to give a pungent gasZ . X, Y and Z, respectively, are:
EASY
In alkaline medium, the reaction of hydrogen peroxide with potassium permanganate produces a compound in which the oxidation state of Mn is
MEDIUM
The manganate and permanganate ions are tetrahedral, due to:
MEDIUM
When a mixture of manganese dioxide, potassium hydroxide and potassium chlorate is fused, the product obtained is
EASY
The ionic charges of manganate and permanganate ion are respectively
MEDIUM
Which of the following is not formed when H2S reacts with acidic K2Cr2O7 solution ?
EASY
Acidified potassium dichromate is treated with hydrogen sulphide. In the reaction, the oxidation number of chromium
MEDIUM
The colour of KMnO4 is due to: [where M metal, L ligand]
MEDIUM
Name the gas that can readily decolourise acidified KMnO4 solution.
MEDIUM
A metal A on heating in nitrogen gas gives compound B. B on treatment with H2O gives a colourless gas which when passed through CuSO4 solution gives a dark blue-violet coloured solution. A and B respectively, are:
MEDIUM
A mixture of NaCl and K2Cr2O7 is heated with conc. H2SO4, deep red vapours and formed. Which of the following statement is false ?
EASY
The number of water molecules not coordinated to copper ion directly in CuSO4·5H2O, is
EASY
An aqueous solution consists of Pb2+ and Cu2+ ions. Which of the following reagents is suitable for separating them?
EASY
When dil. sulphuric acid reacts with aqueous solution of potassium chromate, the colour changes from yellow to orange. This shows that
MEDIUM
MnO2 when fused with KOH and oxidized in air gives a dark green compound X. In acidic solution, X undergoes disproportionation to give an intense purple compound Y and MnO2. The compounds X and Y, respectively, are
MEDIUM
When XO2 is fused with an alkali metal hydroxide in presence of an oxidizing agent such as KNO3; a dark green product is formed which disproportionate in acidic solution to afford a dark purple solution. X is:
HARD
Which one of the following statements is correct when SO2 is passed through acidified K2Cr2O7 solution?