d and f Block Elements
$\mathrm{Nd^{2+}}$ = __________
The correct order of basicity of oxides of vanadium is :
During the qualitative analysis of $\mathrm{SO}_{3}^{2-}$ using dilute $\mathrm{H}_{2} \mathrm{SO}_{4}, \mathrm{SO}_{2}$ gas is evolved which turns $\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ solution (acidified with dilute $\mathrm{H}_{2} \mathrm{SO}_{4}$) :
Given below are two statements :
Statement I : Nickel is being used as the catalyst for producing syn gas and edible fats.
Statement II : Silicon forms both electron rich and electron deficient hydrides.
In the light of the above statements, choose the most appropriate answer from the options given below :
The set of correct statements is :
(i) Manganese exhibits +7 oxidation state in its oxide.
(ii) Ruthenium and Osmium exhibit +8 oxidation in their oxides.
(iii) Sc shows +4 oxidation state which is oxidizing in nature.
(iv) Cr shows oxidising nature in +6 oxidation state.
An indicator 'X' is used for studying the effect of variation in concentration of iodide on the rate of reaction of iodide ion with $\mathrm{H_2O_2}$ at room temp. The indicator 'X' forms blue coloured complex with compound 'A' present in the solution. The indicator 'X' and compound 'A' respectively are :
A chloride salt solution acidified with dil.HNO$_3$ gives a curdy white precipitate, [A], on addition of AgNO$_3$. [A] on treatment with NH$_4$OH gives a clear solution B. A and B are respectively :
Which one amongst the following are good oxidizing agents?
A. Sm$^{2+}$
B. Ce$^{2+}$
C. Ce$^{4+}$
D. Tb$^{4+}$
Choose the most appropriate answer from the options given below :
An ammoniacal metal salt solution gives a brilliant red precipitate on addition of dimethylglyoxime. The metal ion is :
Explanation:
The oxidation state of oxygen is usually -2 and the oxidation state of chlorine is usually -1.
Therefore, we can write:
$\mathrm{Cr} + 2\mathrm{O}(-2) + 2\mathrm{Cl}(-1) = 0$
Simplifying the equation, we get:
$\mathrm{Cr} - 4 - 2 = 0$
$\mathrm{Cr} - 6 = 0$
$\mathrm{Cr} = +6$
Therefore, the oxidation state of chromium in chromyl chloride is $(+6)$.
Explanation:
$\mathrm{MnO_4^-} + \mathrm{I^-} + \mathrm{H^+} \rightarrow \mathrm{Mn^{2+}} + \mathrm{I_2} + \mathrm{H_2O}$
In this reaction, $\mathrm{KMnO}_4$ acts as an oxidizing agent, while $\mathrm{KI}$ acts as a reducing agent. The oxidation state of manganese changes from +7 in $\mathrm{KMnO_4}$ to +2 in $\mathrm{Mn^{2+}}$, which is a reduction of 5 units.
Therefore, the total change in the oxidation state of manganese involved in the reaction is $\boxed{5}$.
Among following compounds, the number of those present in copper matte is ___________.
A. $\mathrm{CuCO_{3}}$
B. $\mathrm{Cu_{2}S}$
C. $\mathrm{Cu_{2}O}$
D. $\mathrm{FeO}$
Explanation:
Copper matte is a mixture of copper sulfide and iron sulfide formed as a result of smelting of copper ore. It contains mainly copper sulfide (Cu2S) as the major component and iron sulfide (FeS) as a minor component.
The compounds A. CuCO3, C. Cu2O, and D. FeO are not present in copper matte, but can be formed as a result of further processing or refining of the matte.
Therefore, among the given compounds, only "B. Cu2S" is present in copper matte.
The number of electrons involved in the reduction of permanganate to manganese dioxide in acidic medium is _____________.
Explanation:
$\mathrm{3{e^ - } + 4{H^ + } + MnO_4^ - \buildrel {} \over \longrightarrow Mn{O_2} + 2{H_2}O}$
How many of the following metal ions have similar value of spin only magnetic moment in gaseous state? ______________
(Given : Atomic number V, 23; Cr, 24; Fe, 26; Ni, 28)
V$^{3+}$, Cr$^{3+}$, Fe$^{2+}$, Ni$^{3+}$
Explanation:
$ \begin{array}{ll} & n \\ \mathrm{V}^{3+}:[\mathrm{Ar}] 3 \mathrm{~d}^2 4 \mathrm{~s}^0 & 2 \\\\ \mathrm{Cr}^{3+}:[\mathrm{Ar}] 3 \mathrm{~d}^3 4 \mathrm{~s}^0 & 3 \\\\ \mathrm{Fe}^{2+}:[\mathrm{Ar}] 3 \mathrm{~d}^6 4 \mathrm{~s}^0 & 4 \\\\ \mathrm{Ni}^{3+}:[\mathrm{Ar}] 3 \mathrm{~d}^7 4 \mathrm{~s}^0 & 3 \end{array} $
$\mathrm{Cr}^{3+} ~\&~ \mathrm{Ni}^{3+}$ have same value of $\mu_{\mathrm{s}}$
The product formed during thermal decomposition of ammonium dichromate are
$\mathrm{O}_2, \mathrm{H}_2 \mathrm{O}, \mathrm{Cr}(\mathrm{OH})_3$
$\mathrm{NO}_2, \mathrm{H}_2 \mathrm{O}, \mathrm{Cr}_2 \mathrm{O}_3$
$\mathrm{N}_2, \mathrm{Cr}_2 \mathrm{O}_3, \mathrm{H}_2 \mathrm{O}$
$\mathrm{N}_2 \mathrm{O}, \mathrm{Cr}(\mathrm{OH})_3$
In +2 oxidation state, which of the following lanthanoids act as reducing agents?
$\mathrm{Ce}, \mathrm{Pr}$
Eu, Gd
Eu, Yb
Lu, Er
Among the following the incorrect statement about transition metals is
$\mathrm{Cr}, \mathrm{Mo}$ and W have high melting points.
With increase in number of unpaired. electrons melting point increases.
$\mathrm{Mn}^{3+}$ is more stable than $\mathrm{Mn}^{2+}$.
They show variable oxidation states.
Observe the following ions
$ \mathrm{V}^{2+}, \mathrm{Zn}^{2+}, \mathrm{Cu}^{2+}, \mathrm{Fe}^{2+}, \mathrm{Fe}^{3+}, \mathrm{Ti}^{3+}, \mathrm{Sc}^{3+}, \mathrm{Ti}^{4+}, \mathrm{Ni}^{3+}, \mathrm{Co}^{3+}, \mathrm{Cu}^{+} $
How many ions in the above list have zero magnetic moment?
4
3
5
2
The order of melting points of $\mathrm{Cr}, \mathrm{Mo}$ and W is
Which of the following $3\mathrm{d}$-metal ion will give the lowest enthalpy of hydration $\left(\Delta_{\text {hyd }} \mathrm{H}\right)$ when dissolved in water ?
The reaction of zinc with excess of aqueous alkali, evolves hydrogen gas and gives :
In following pairs, the one in which both transition metal ions are colourless is :
In neutral or faintly alkaline medium, $\mathrm{KMnO}_{4}$ being a powerful oxidant can oxidize, thiosulphate almost quantitatively, to sulphate. In this reaction overall change in oxidation state of manganese will be :
Match List - I with List - II, match the gas evolved during each reaction.
| List - I | List - II | ||
|---|---|---|---|
| (A) | $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{Cr}_{2} \mathrm{O}_{7} \stackrel{\Delta}{\longrightarrow}$ | (I) | $\mathrm{H}_{2}$ |
| (B) | $\mathrm{KMnO}_{4}+\mathrm{HCl} \rightarrow$ | (II) | $\mathrm{N}_{2}$ |
| (C) | $\mathrm{Al}+\mathrm{NaOH}+\mathrm{H}_{2} \mathrm{O} \rightarrow$ | (III) | $\mathrm{O}_{2}$ |
| (D) | $\mathrm{NaNO}_{3} \stackrel{\Delta}{\longrightarrow}$ | (IV) | $\mathrm{Cl}_{2}$ |
Choose the correct answer from the options given below :
Which of the following has least tendency to liberate $\mathrm{H}_{2}$ from mineral acids?
In neutral or alkaline solution, $\mathrm{MnO}_{4}^{-}$ oxidises thiosulphate to :
Given below are two statements.
Statement I : Iron (III) catalyst, acidified $\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ and neutral $\mathrm{KMnO}_{4}$ have the ability to oxidise $\mathrm{I}^{-}$ to $\mathrm{I}_{2}$ independently.
Statement II : Manganate ion is paramagnetic in nature and involves $\mathrm{p} \pi-\mathrm{p} \pi$ bonding.
In the light of the above statements, choose the correct answer from the options given below.
The total number of $\mathrm{Mn}=\mathrm{O}$ bonds in $\mathrm{Mn}_{2} \mathrm{O}_{7}$ is __________.
The dark purple colour of $\mathrm{KMnO}_{4}$ disappears in the titration with oxalic acid in acidic medium. The overall change in the oxidation number of manganese in the reaction is :
The electronic configuration of Pt (atomic number 78) is :
Which one of the lanthanoids given below is the most stable in divalent form?
[Given : Atomic no. Eu, 63; Sm, 62; Tm, 69; Tb, 65; Yb, 70; Dy, 66]
The most common oxidation state of Lanthanoid elements is +3. Which of the following is likely to deviate easily from +3 oxidation state?
The metal ion (in gaseous state) with lowest spin-only magnetic moment value is :
Cerium (IV) has a noble gas configuration. Which of the following is correct statement about it?
Among the following, which is the strongest oxidizing agent?
Metals generally melt at very high temperature. Amongst the following, the metal with the highest melting point will be :
The disproportionation of $\mathrm{MnO}_{4}^{2-}$ in acidic medium resulted in the formation of two manganese compounds $\mathrm{A}$ and $\mathrm{B}$. If the oxidation state of $\mathrm{Mn}$ in $\mathrm{B}$ is smaller than that of A, then the spin-only magnetic moment $(\mu)$ value of B in BM is __________. (Nearest integer)
Explanation:
$\mathrm{Mn} \rightarrow 4 s^{2} 3 d^{5}$
$\mathrm{Mn}^{+4} \rightarrow 3 d^{3}$
$ \mathrm{n}=3 $
$ \begin{aligned} \mu &=\sqrt{n(n+2)} \\\\ &=\sqrt{3(5)} \\\\ &=\sqrt{15} \\\\ &=3.87 \approx 4 \text { B.M. } \end{aligned} $
The spin-only magnetic moment value of the compound with strongest oxidizing ability among $\mathrm{MnF}_{4}, \mathrm{MnF}_{3}$ and $\mathrm{MnF}_{2}$ is ____________ B.M. [nearest integer]
Explanation:
$ \left[\begin{array}{l} \mathrm{E}_{\mathrm{Mn}^{+3} / \mathrm{Mn}^{+2}}^{\circ} \simeq 1.57 \mathrm{~V} \\ \& \,\,\mathrm{E}_{\mathrm{Mn}^{+4} / \mathrm{Mn}^{+2}}^{\circ} \simeq 1.2 \mathrm{~V} \end{array}\right] $
So, spin only magnetic moment
$ =\sqrt{4(4+2)}=\sqrt{24} \text { B.M. } $
$\simeq 5$
Among Co3+, Ti2+, V2+ and Cr2+ ions, one if used as a reagent cannot liberate H2 from dilute mineral acid solution, its spin-only magnetic moment in gaseous state is ___________ B.M. (Nearest integer)
Explanation:
$\mathrm{E}_{\mathrm{Co}^{3+}/\mathrm{Co}^{2+}}^{\mathrm{O}}=+1.97$
And $\mathrm{Co}^{3+}$ has electronic configuration $=[\operatorname{Ar}] 3 d^{6}$
$\therefore 4$ unpaired $\mathrm{e}^{-}$ are present in it
$\therefore$ Spin-only magnetic moment $=\sqrt{4(4+2)} =4.92 \approx 5$
Spin only magnetic moment of [MnBr6]4$-$ is _________ B.M. (round off to the closest integer)
Explanation:
$ \begin{aligned} x & =+2 \\\\ \mathrm{Mn} & =[\mathrm{Ar}] 3 d^5 4 s^2 \\\\ \mathrm{Mn}^{2+} & =[\mathrm{Ar}] 3 d^5 4 s^0 \end{aligned} $
So, number of unpaired electrons $(n)=5$
$ \begin{aligned} \mu & =\sqrt{n(n+2)} \\\\ \mu & =\sqrt{5(5+2)} \\\\ & =\sqrt{35} \\\\ & =5.91 \text { B.M. } \\\\ & \approx 6 \text { B.M. } \end{aligned} $
For the reaction given below :
CoCl3 . xNH3 + AgNO3 (aq) $\to$
If two equivalents of AgCl precipitate out, then the value of x will be _____________.
Explanation:
The number of terminal oxygen atoms present in the product B obtained from the following reaction is _____________.
FeCr2O4 + Na2CO3 + O2 $\to$ A + Fe2O3 + CO2
A + H+ $\to$ B + H2O + Na+
Explanation:
$ \mathrm{Na}_{2} \mathrm{CrO}_{4}+\mathrm{H}^{+} \longrightarrow \mathrm{Cr}_{2} \mathrm{O}_{7}^{-2}+\mathrm{H}_{2} \mathrm{O}+\overset{+}{\mathrm{Na}} $
An acidified manganate solution undergoes disproportionation reaction. The spin-only magnetic moment value of the product having manganese in higher oxidation state is _____________ B.M. (Nearest integer)
Explanation:
The number of statements correct from the following for Copper (at. no. 29) is/are ____________.
(A) Cu(II) complexes are always paramagnetic.
(B) Cu(I) complexes are generally colourless
(C) Cu(I) is easily oxidized
(D) In Fehling solution, the active reagent has Cu(I)
Explanation:
(B) $\mathrm{Cu}(\mathrm{I})$ complexes are generally colourless due to $d^{10}$ configuration.
(C) $\mathrm{Cu}(\mathrm{I})$ is easily oxidised to $\mathrm{Cu}^{+2}$ in aqueous solution
$2 \mathrm{Cu}^{+} \rightarrow \mathrm{Cu}^{+2}+\mathrm{Cu}$
$\mathrm{Cu}^{+1}$ disproportionates to $\mathrm{Cu}^{+2}$ and $\mathrm{Cu}$
$\left(E_{\text {cell }}^{\circ}>0\right.$ for this cell reaction in aqueous solution)
In Fehling's solution, active reagent has $\mathrm{Cu}(\mathrm{II})$ which is reduced to $\mathrm{Cu}(\mathrm{I})$ on reaction with aldehydes.
Hence (D) statement is incorrect
The spin-only magnetic moment value of the most basic oxide of vanadium among V2O3, V2O4 and V2O5 is _____________ B.M. (Nearest integer)
Explanation:
$ \mathrm{V}_{2} \mathrm{O}_{3}=\mathrm{V}^{+3}\left(\mathrm{~d}^{2}\right) $
Magnetic moment $=\sqrt{2(2+2)}=\sqrt{8}$
$ =2.83 \approx 3 $