Reactivity of Lanthanides

Q.

What are the characteristics of s, p , d, f block elements?

Q. The trend of basicity of lanthanoid hydroxides:

1. increases across the lanthanoid series
2. decreases across the lanthanoid series
3. first increases and then decreases
4. first decreases and then increases

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. (i) There are four d-block series.
(ii) Total d-block elements are 40.
(iii) Last d-block series starts with element actinium.
(iv) All members of d-block series are transition metal.
The correct statements are :

1. (i), (ii) and (iii)
2. (i) and (iii)
3. (i) and (v)
4. All

Q. Which of the following lanthanoids show +2 oxidation state besides the characteristic oxidation state +3 of lanthanoids?

1. Ce
2. Eu
3. Yb
4. Ho

Q.

Beryllium is placed above magnesium in the second group. Beryllium dust,

therefore when added to MgCl₂ solution will

[CPMT 1977]

1. Precipitate Mg metal

2. Have no effect

3. Precipitate MgO

4. Lead to dissolution of Be metal

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. KF combines with HF to form $KH{F}_2$. The compound contains the species

1. 
2. 
3. 
4. 

Q. Which of the following is the most covalent halide?

1. $Al{F}_3$
2. $AlB{r}_3$
3. $AlC{l}_3$
4. $Al{I}_3$

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. ferric iodide is a covalent compound whereas ferric chloride is ionic
3. $I^{-}$ 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.
4. ferric iodide is a covalent compound whereas ferric chloride is ionic

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. c
2. d
3. a
4. b

Q. In aqueous solution $E{u}^{2+}$ ion act as :

1. An oxidizing agent
2. None of these
3. Either A or B
4. A reducing agent

Q. Which one of the following statements concerning lanthanides elements is false?

1. Lanthanides are separated from one another by ion exchange methods
2. The ionic radii of trivalent lanthanides steadily increase with increase in atomic number
3. All lanthanides are highly dense metals
4. Most typical oxidation of lanthanides is +3

Q. Consider the following statements :
(i) $La(OH{)}_3$ is the least basic among hydroxides of lanthanoid
(ii) $Z{r}^{4+}$ and $H{f}^{4+}$ possess almost the same ionic radii
(iii) $C{e}^{4+}$ can act as an oxidizing agent.

1. (i) and (iii)
2. (ii) and (iii)
3. (ii) only
4. (i) and (ii)

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. Which of the following is not a consequence of lanthanide contraction?

1. From $L{a}^{+3}\text{to}L{u}^{+3}$, the ionic radii changes from 106 pm to 85 pm.
2. As the size of the lanthanide ions decreases the basic strength increases.
3. The atomic radii of 4d and 5d series is similar.
4. None of the above

Q. Salts of manganese ion is generally :

1. pink
2. blue
3. red
4. none of the above

Q. (a) Account for the following:
(i) Transition metals show variable oxidation states.
(ii) Zn, Cd and Hg are soft metals.
(iii) $E^o$ value for the $M{n}^{3+}/M{n}^{2+}$ couple is highly positive (+ 1.57 V) as compared to $C{r}^{3+}/C{r}^{2+}$.
(b) Write one similarity and one difference between the chemistry of lanthanoid and actinoid elements.

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