d and f Block Elements · Chemistry · COMEDK
MCQ (Single Correct Answer)
Choose the correct metal/ ion from the brackets which -------------------------
A. has chemical reactivity similar to that of the first few members of the Lanthanoids $(\mathrm{Zn}, \mathrm{Ca}, \mathrm{Fe}, \mathrm{Cu})$.
B. has stable $4 \mathrm{f}^7$ electronic configuration, but acts as a strong reducing agent and converts to $\mathrm{M}^{3+}$ state. $\left(\mathrm{Eu}^{2+}, \mathrm{Ce}^{2+}, \mathrm{Pr}^{2+}, \mathrm{Dy}^{2+}\right)$
C. is a colorless ion $\left(\mathrm{Tm}^{3+}, \mathrm{Lu}^{3+}, \mathrm{Gd}^{3+}, \mathrm{Sm}^{3+}\right)$.
D. shows stable +2 oxidation state and is diamagnetic ( $\mathrm{Ce}, \mathrm{Sm}, \mathrm{Ho}, \mathrm{Yb}$ )
Find the correct matches.
| A. | $\mathrm{Cr}_2 \mathrm{O}_7^{2-}$ | P. | is predominantly a basic compound. |
|---|---|---|---|
| B. | $\mathrm{FeCr}_2 \mathrm{O}_4$ | Q. | is predominantly a acidic compound |
| C. | $\mathrm{CrO}_3$ | R. | forms yellow chromate on reaction with $\mathrm{Na}_2 \mathrm{CO}_3$ in air. |
| D. | $\mathrm{CrO}$ | S. | is interconvertible with $\mathrm{MO}_4^{2-}$ depending on the pH of the medium. |
Choose the statements which are incorrect in the case of Lanthanoids.
A. $\mathrm{Ce}^{4+}$ is diamagnetic while $\mathrm{Sm}^{3+}$ is paramagnetic.
B. The atomic size of the transition metals having atomic number greater than 71 are very close to that of the elements above them.
C. Lanthanoids react with hot water forming water soluble $\mathrm{Ln}(\mathrm{OH})_3$ with the liberation of $\mathrm{O}_2$.
D. The general electronic configuration of Lanthanoids is $(n-2) \mathrm{f}^{1-14} 5 \mathrm{~d}^0 6 \mathrm{~s}^2$, where $n=6$.
Which is the correct order of increasing number of unpaired electrons in the following ions?
$$\mathrm{A}=\mathrm{Cr}^{2+}(\mathrm{Z}=24) \mathrm{B}=\mathrm{Cu}^{2+}(\mathrm{Z}=29) \quad \mathrm{C}=\mathrm{Ni}^{2+}(\mathrm{Z}=28) \mathrm{D}=\mathrm{Fe}^{3+}(\mathrm{Z}=26)$$
A. $=$ chromate $\mathrm{B}=$ permanganate $\mathrm{C}=$ dichromate
Match the metals in Column II with their characteristic properties given in Column I.
| Properties | Metals | ||
|---|---|---|---|
| A. | Lanthanoid with low value of $3^{\text {rd }}$ ionisation enthalpy. | P | V |
| B. | f-Block element with electronic configuration $[R n] 6 d^2 7 s^2$ | Q | Gd |
| C. | 3 d -series metal whose $\mathrm{M}^{3+}{ }_{(\mathrm{aq})}$ is colourless. | R | Th |
| D. | 3d-series metal with highest $\Delta \mathrm{H}_{\text {(atomisation) }}$ | S | Sc |
What is the spin only magnetic moment of the metal ion in $\mathbf{P}$ and the oxidation number of Sulphur in the oxidised product Z ?
Identify the correct statement from the following.
An inorganic compound $$\mathrm{W}$$ undergoes the following reactions:
$$ \begin{gathered} W+\frac{\mathrm{Na}_2 \mathrm{CO}_3}{\mathrm{O}_2 / \text { heat }} \rightarrow X+\frac{\mathrm{H}^{+}}{} \rightarrow Y_{(s)} \\ Y(a q)+\mathrm{KCl}(\mathrm{aq}) \rightarrow Z_{(S)} \end{gathered} $$
Z appears in the form of orange crystals and is used as an oxidising agent in acid medium. Identify the compound W.
The Lanthanoid ion which would form coloured compounds is -------------.
Atomic numbers: $$\mathrm{Yb}=70, \quad \mathrm{Lu}=71, \mathrm{Pr}=59, \quad \mathrm{La}=57$$
The metallic ions that have almost same spin only magnetic moment are :
(i) $$\mathrm{Co}^{2+}$$
(ii) $$\mathrm{Mn}^{2+}$$
(iii) $$\mathrm{Cr}^{2+}$$
(iv) $$\mathrm{Cr}^{3+}$$
The correct order of increasing melting point is
Consider the following statements in respect of lanthanides, which of the statements are incorrect?
(i) $$\mathrm{La}(\mathrm{OH})_3$$ is least basic among the hydroxides of lanthanides
(ii) The lanthanide ions $$\mathrm{Yb}^{2+}, \mathrm{Lu}^{3+}$$ and $$\mathrm{Ce}^{4+}$$ are diamagnetic in nature.
(iii) $$\mathrm{Ce}^{4+}$$ can act as an oxidising agent
(iv) $$\operatorname{Ln}$$ (III) compounds are generally colourless
(v) Ionic radii of $$\mathrm{Ce}^{3+}$$ is greater than $$\mathrm{Yb}^{3+}$$
Arrange the following ions in the increasing order of their $$\Delta H_{(\text {hydration})}$$ values.
$$\mathrm{Cr}^{2+}, \mathrm{Co}^{2+}, \mathrm{Mn}^{2+}, \mathrm{Ni}^{2+}$$
The permanganate ion in acid medium acts as an oxidant and gets converted to its lower oxidation state. What would be the spin only magnetic moment of such reduced manganese ion?
Match the compounds given in Column I with their characteristic features listed in Column II
| No. | Column I | No. | Column II |
|---|---|---|---|
| A | $$ \mathrm{La}(\mathrm{OH})_3 $$ |
P | Acidic in nature |
| B | $$ \mathrm{Mn}_2 \mathrm{O}_7 $$ |
Q | Least basic |
| C | $$ \mathrm{Lu}(\mathrm{OH}) 3 $$ |
R | Interstitial compound |
| D | $$ \mathrm{Fe}_3 \mathrm{H} $$ |
S | Most basic |
Choose the incorrect statement from the following
$$\mathrm{Ti}^{2+}$$ is purple while $$\mathrm{Ti}^{4+}$$ is colourless because
A volatile compound is formed by carbon monoxide and
Match the following characteristics of transition metals given in Column I with the examples listed in Column II
| S. No. | Characteristic properties | S. No. | Examples |
|---|---|---|---|
| W | Chemically inert, non-stoichiometric compound | A | $$\mathrm{WO}_3$$ |
| X | Higher oxidation states are more stable | B | $$\mathrm{TiCl_4}$$ |
| Y | Due to inert pair effect, lower oxidation state is more stable | C | $$\mathrm{Mn_4N}$$ |
| Z. | Colourless compound of transition metal | D | $$\mathrm{SnCl_2}$$ |
Find the correct matches of the substances, given in Column I, from their characteristic properties given in Column II.
| S.No. | Column I | S.No. | Column II |
|---|---|---|---|
| W | $$ \mathrm{Tl} $$ |
A | Decomposes steam to form its dioxide and dihydrogen gas. |
| X | $$ \mathrm{CCl}_4 $$ |
B | Consists of twenty 6 -membered rings and twelve 5 membered rings. |
| Y | $$\mathrm{Tin}$$ | C | +3 oxidation state is highly oxidising. |
| Z | $$ \mathrm{C_{60}} $$ |
D | Electron precise species, neither acts as electron donor nor as electron acceptor. |
Identify the incorrect statement.
An aqueous solution of X on addition of hydrogen peroxide in ice cold conditions gives blue colour to the ethereal layer. Then, X can be
In 3d-transmission series, which one has the least melting point?
The electronic configuration of Cr$$^{3+}$$ is
Formation of coloured solution is possible, when metal ion in the compound contains
Which of the following forms a colourless solution in aqueous medium?