d and f Block Elements
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 $\mu_{\mathrm{s}}$
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 $
Manganese (VI) has ability to disproportionate in acidic solution. The difference in oxidation states of two ions it forms in acidic solution is ____________.
Explanation:
$3 \mathrm{MnO}_{4}^{2-}+4 \mathrm{H}^{+} \longrightarrow 2 \mathrm{MnO}_{4}^{-}+\mathrm{MnO}_{2}+2 \mathrm{H}_{2} \mathrm{O}$
The difference in oxidation states of $\mathrm{Mn}$ in the products formed $=7-4=3$
The difference in oxidation state of chromium in chromate and dichromate salts is ___________.
Explanation:
Dichromate ion $\rightarrow \mathrm{Cr_2O}_{7}^{2-}$, oxidation state of $\mathrm{Cr}=+6$
$\therefore $ Difference in oxidation state $=$ zero
Which of the following pair is not isoelectronic species?
(At. no. Sm, 62; Er, 68; Yb, 70; Lu, 71; Eu, 63; Tb, 65; Tm, 69)
5Fe2+ + MnO$_4^ - $ + 8H+ $\to$ Mn2+ + 4H2O + 5Fe3+
| X = basic | Y = amphoteric |
| X = amphoteric | Y = basic |
| X = acidic | Y = acidic |
| X = basic | Y = basic |
(At.No. Sc : 21, Ti : 22, V : 23)
(a) CrO3, (b) Fe2O3, (c) MnO2, (d) V2O5, (e) Cu2O
| List - I |
List - II |
||
|---|---|---|---|
| (a) | Chlorophyll | (i) | Ruthenium |
| (b) | Vitamin-${B_{12}}$ | (ii) | Platinum |
| (c) | Anticancer drug | (iii) | Cobalt |
| (d) | Grubbs catalyst | (iv) | Magnesium |
Choose the most appropriate answer from the options given below :