Lanthanoids are

14 elements in the sixth period (atomic no. = 90 to 103)that are filling 4f sublevel
14 elements in the seventh period (atomic no. =90 to 103) that are filling 5f sublevel
14 elements in the sixth period (atomic no. =58 to 71)that are filling 4f sublevel
14 elements in the seventh period (atomic no. =58 to 71) that are filling 4f sublevel

Solution

Lanthanides are 4 f-series elements starting from cerium(Z= 58) to lutetium (Z= 71). These are placed in the sixth period and in third group.

Cuprous chloride is used in gas analysis to absorb?

Solution

A solution of CuCl in NH₄OH is often used to measure the amount of CO in gas samples, by measuring the change in volume of the gas.

Among the following which is used as an electrolyte in electroplating a base metal with gold?

Solution

Complex soluble salts of the metal to be deposited are usually employed as electrolytes in electroplating.Hence K[Au(CN)₂] is used as an electrolyte in gold plating.

Which one of the following elements shows maximum number of different oxidation states in its compounds?

Solution

We know that lanthanides La, Gd shows +3, oxidation state, while Eu shows oxidation state of +2 and + 3. Am shows +3, +4, +5 and +6 oxidation states. Therefore Americium (Am) has maximum number of oxidation states

The lanthanoide contraction is responsible for the fact that

(Atomic numbers: Zr = 40, Y= 39, Nb = 41, Hf = 72, Zn = 30)

Solution

A regular decrease in the size of the atoms and ions in lanthanoid series from La³⁺ to Lu³⁺ is called lanthanide contraction. The similarity in size of the atoms of Zr and Hf is due to the lanthanide contraction.

Both acid and base may react with which of the following oxides ?

Among the lanthanoides the one obtained by synthetic method is

Bessemer converter is used in the manufacture of

KMnO₄(acidic/alkaline) is not decolourised by

Solution

Benzene does not decolourise KMnO₄(acidic/alkaline).It is due to the delocalization of π-electron in benzene.Mohr’s salt and oxalic acid gives redox reaction with KMnO₄. Propene decolorises KMnO₄ due to presence of C = C bond.

The final products formed on the addition of KI to copper sulphate solution are :

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