Reactivity of Lanthanides

Q. How is the valency of manganese +2 and not -1?

Q. Which one of the following statements related to lanthanides is incorrect?

1. Europium shows +2 oxidation state.
2. The basicity decreases as the ionic radius decreases from Pr to Lu.
3. All the lanthaides are much more reactive than aluminium.
4. Ce (+4) solutions are widely used as oxidizing agent in volumetric analysis.

Q. Read the assertion and reason carefully to mark the correct option out of the options given below:

(a)If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b)If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c)If assertion is true but reason is false.

(d)If assertion is false but reason is true.
Assertion : EV(M${}^{2+}$/M) value for copper is positive (+0.34V).
Reason : High ionization enthalpy and low heat of hydration energy

1. a
2. b
3. c
4. d

Q. Ferric iodide is very unstable but ferric chloride is a stable compound. This is because

1. hydration energy of ferric iodide is less than that of ferric chloride
2. $I^{-}$ ion is a stronger reducing agent as compared to $C{l}^{-}$ ion and thus, $F{e}^{3+}$ is easily reduced by $I^{-}$ ion to $F{e}^{2+}$ ion.
3. ferric iodide is a covalent compound whereas ferric chloride is ionic
4. ferric iodide is a covalent compound whereas ferric chloride is ionic

Q. Ferric iodide is very unstable but ferric chloride is a stable compound. This is because

1. hydration energy of ferric iodide is less than that of ferric chloride
2. $I^{-}$ ion is a stronger reducing agent as compared to $C{l}^{-}$ ion and thus, $F{e}^{3+}$ is easily reduced by $I^{-}$ ion to $F{e}^{2+}$ ion.
3. ferric iodide is a covalent compound whereas ferric chloride is ionic
4. ferric iodide is a covalent compound whereas ferric chloride is ionic