Assertion (A) : Actinoids show wide range of oxidation states.
Reason (R) : Actinoids are radioactive in nature.
CBSE CLASS 12 • CHEMISTRY • CHAPTER 04
The d- and f-Block Elements
169 distinct questions across 213 board paper set appearances (2022–2026).
Assertion (A) : Zinc, cadmium and mercury are not considered as transition elements.
Reason (R) : These elements have completely filled orbitals in their ground state as well as in their common oxidation states.
Actinoids show larger number of oxidation states :
(A) because they are radioactive in nature
(B) because they have large atomic numbers
(C) because they have large atomic masses
(D) due to comparable energies of $5\text{f}$, $6\text{d}$ and $7\text{s}$ orbitals
Atomic radii is a useful property for determining many aspects of chemistry of elements such as physical and chemical properties. The periodic table greatly assists in finding a number of trends. The transition metals belong to group $3 - 12$ and are generally characterised by partially filled d-orb...
(c) Why is there not much change in the atomic radius of the transition metals with the increase in atomic number ?
Give explanation for each of the following observations :
(a) With the same d-orbital configuration ($d^4$), $\text{Mn}^{3+}$ ion is an oxidising agent whereas $\text{Cr}^{2+}$ ion is a reducing agent.
(b) Actinoid contraction is greater from element to element than that among lanthanoids.
(c) Trans...
The transition element which shows both $+1$ and $+2$ oxidation states is :
(A) $\text{Sc}$
(B) $\text{Mn}$
(C) $\text{Cu}$
(D) $\text{Zn}$
The most common and stable oxidation state of a Lanthanoid is :
(a) + 2
(b) + 3
(c) + 4
(d) + 6
Assertion (A): Zinc is not regarded as a transition element.
Reason (R): In zinc, 3d orbitals are completely filled in its ground state as well as in its oxidised state.
OR (b) (i) Identify the following : (1) Transition metal of 3d series that exhibits only one oxidation state. (2) Transition metal of 3d series that acts as a strong reducing agent in +2 oxidation state in aqueous solution. (ii) Complete and balance the following equations : (1) $\text{Cr}_2\text{O}...
Which property of transition metals enables them to behave as catalysts?
(a) High melting point
(b) High ionisation enthalpy
(c) Alloy formation
(d) Variable oxidation states
The most common oxidation state for all lanthanoids is :
(a) + 5
(b) + 2
(c) + 3
(d) + 4
(a) (i) Which is the most common oxidation state in Lanthanoids ? (ii) Why is there a gradual decrease in the atomic sizes of transition metals in a series with increasing atomic numbers ? (iii) Calculate the number of unpaired electrons in the following gaseous ions : $V^{3+}$, $Ti^{3+}$
(a) (i) Account for the following :
(I) $\text{MnO}$ is basic while $\text{Mn}_2\text{O}_7$ is acidic.
(II) Iron has higher enthalpy of atomization than that of copper.
(III) $\text{Mn}^{3+}$ is a stronger oxidising agent than $\text{Cr}^{3+}$.
(ii) How do you prepare potassium dichromate from sodiu...
(a) (i) Why do $\text{Zr}$ and $\text{Hf}$ exhibit similar properties ?
(ii) "$E^{\circ}$ for $\text{Mn}^{3+}/\text{Mn}^{2+}$ couple is more positive than that for $\text{Fe}^{3+}/\text{Fe}^{2+}$." Justify the statement.
[Atomic number : $\text{Mn} = 25$, $\text{Fe} = 26$]
OR
(b) (i) Which element i...
(b) (i) Why is Zn a non-transition element ?
(a) (i) When pyrolusite ore is fused with $ ext{KOH}$, in presence of air, a dark green coloured product 'A' is obtained which changes to purple coloured compound 'B' in acidic medium.
(I) Write the formulae of 'A' and 'B'.
(II) Write the ionic equation for the reaction when compound 'B' reacts with...
Answer the following questions :
(i) What is 'Misch metal' ? Give its one use.
(ii) Write the formula of an oxoanion of chromium in which it shows the oxidation state equal to its group number.
(iii) Why does Vanadium pentoxide ($ ext{V}_2 ext{O}_5$) act as a catalyst ?
(iv) Why do transition elemen...
(a) (i) Account for the following :
(I) The $E^{\circ}_{\text{Mn}^{2+}/\text{Mn}}$ value for manganese is highly negative, whereas $E^{\circ}_{\text{Mn}^{3+}/\text{Mn}^{2+}}$ is highly positive.
(II) Actinoids show wide range of oxidation states.
(III) Transition metals have high melting points.
Assertion (A) : Actinoids show a wide range of oxidation states.
Reason (R) : Actinoids are radioactive in nature.
(a) (i) Write the chemical equations involved in the preparation of potassium permanganate from pyrolusite ore (\text{MnO}_2).
(ii) Give reasons for the following :
(I) Sc (Atomic No. 21) salts are white.
(II) $E^\circ_{\text{Cu}^{2+}|\text{Cu}}$ is positive whereas $E^\circ_{\text{Mn}^{2+}|\text{Mn...
(a) Why do transition metals and their compounds act as good catalysts ?
(b) What is the cause of contraction in the atomic size of lanthanoids ?
(c) Define lanthanoid contraction. How does it affect the atomic radii of the third transition series and the second transition series ?
The involvement of $(n - 1)d$ electrons in the behaviour of transition elements impart certain distinct characteristics to these elements. Thus, in addition to variable oxidation states, they exhibit paramagnetic behaviour, catalytic properties and tendency for the formation of coloured ions. The tr...
Assign reason for each of the following : (i) Manganese exhibits the highest oxidation state of $+7$ among the 3d series of transition elements. (ii) Transition metals and their compounds are generally found to be good catalysts in chemical reactions. (iii) $\text{Cr}^{2+}$ is reducing in nature whi...
(a) (i) Account for the following : (1) $\text{Zn}^{2+}$ salts are colourless while $\text{Ni}^{2+}$ salts are coloured. (2) $\text{Cr}^{2+}$ is a strong reducing agent. (3) Transition metals and their compounds show catalytic activities. (ii) Write the ionic equations for the oxidizing action of $\...
Answer the following questions : (a) The chemistry of the actinoids is more complex as compared to lanthanoids. Why ? (b) Why is $E^{\circ}$ for $\text{Mn}^{3+}/\text{Mn}^{2+}$ redox couple more positive ? (c) Why do transition metals form large numbers of complex compounds ? (d) How does acidified ...
Assertion (A) : $\text{Zn}$, $\text{Cd}$ and $\text{Hg}$ are not regarded as transition elements. Reason (R) : $\text{Zn}$, $\text{Cd}$ and $\text{Hg}$ do not have partially filled $\text{d-orbitals}$ in their ground state or in any one of their common oxidation states.
Account for the following : (i) Transition metals and their compounds show catalytic activities. (ii) $\text{Zn}$, $\text{Cd}$ and $\text{Hg}$ are non-transition elements. (iii) $\text{Zr}$ and $\text{Hf}$ are of almost identical atomic radii.
(i) Silver atom has completely filled d-orbitals in its ground state, it is still considered to be a transition element. Justify the statement.
(ii) Why are E^{\ominus}_{M^{2+}/M} values of Mn and Zn more negative than expected ?
(iii) Why do transition metals form alloys ?
(a) Write any two consequences of Lanthanoid Contraction. (b) Name the element of 3d series which exhibits the largest number of oxidation states. Give reason.
Which of the following is not a transition metal ?
(A) $\text{Sc}$
(B) $\text{Ag}$
(C) $\text{Hg}$
(D) $\text{Cu}$
(a) (i) From the given data of $E^\circ$ values, answer the following questions :
[Table showing $E^\circ_{ ext{M}^{2+}/ ext{M}}$ values for V (-1.18), Cr (-0.91), Mn (-1.18), Fe (-0.44), Co (-0.28), Ni (-0.25), Cu (+0.34)]
(I) Why $E^\circ_{ ext{M}^{2+}/ ext{M}}$ show irregular trend in the above v...
(b) Answer the following questions :
(i) Name a member of the lanthanoid series
(I) which exhibits $+4$ oxidation state
(II) which exhibits $+2$ oxidation state.
(ii) Why transition metals act as good catalyst ?
(iii) Why $ ext{Cr}$ has higher melting point than $ ext{Mn}$ ?
(iv) What happens when a...
Assertion (A) : Actinoids show irregularities in their electronic configurations.
Reason (R) : In actinoids $5\text{f}$, $6\text{d}$ and $7\text{s}$ orbitals are of comparable energies.
(a) (i) From the given data of $E^{\circ}$ values, answer the following questions :
| $E^{\circ}_{M^{2+}/M}$ | V | Cr | Mn | Fe | Co | Ni | Cu |
|---|---|---|---|---|---|---|---|
| | $-1.18$ | $-0.91$ | $-1.18$ | $-0.44$ | $-0.28$ | $-0.25$ | $+0.34$ |
(I) Why $E^{\circ}_{M^{2+}/M}$ show irregular...
Which of the following transition metals has lowest enthalpy of atomisation ?
(A) $\text{Cr}$
(B) $\text{V}$
(C) $\text{Mn}$
(D) $\text{Fe}$
Assertion (A) : Actinoids show irregularities in their electronic configurations.
Reason (R) : Due to varying stabilities of $\text{f}^0$, $\text{f}^7$ and $\text{f}^{14}$ occupancies of the 5f orbitals.
31. (a) (i) From the given data of $E^{\circ}$ values, answer the following questions :
| $E^{\circ}_{M^{2+}/M}$ | V | Cr | Mn | Fe | Co | Ni | Cu |
|---|---|---|---|---|---|---|---|
| | $-1.18$ | $-0.91$ | $-1.18$ | $-0.44$ | $-0.28$ | $-0.25$ | $+0.34$ |
(I) Why $E^{\circ}_{M^{2+}/M}$ show irreg...
(a) First ionization enthalpy of $\text{Cr}$ is lower than that of $\text{Zn}$. Why ?
(b) Mention any one property of the transition elements which makes them good catalysts.
(a) Complete and balance the following equations :
(i) $2\text{KMnO}_4 \xrightarrow{513\text{ K}}$
(ii) $\text{Na}_2\text{Cr}_2\text{O}_7 + 2\text{KCl} \longrightarrow$
(b) Why is it difficult to separate lanthanoid elements in pure state ?
(a) Why is third ionization enthalpy of manganese very high ?
(b) Why $\text{Zn}$, $\text{Cd}$ and $\text{Hg}$ are not regarded as transition elements ?
(a) Complete and balance the following equations :
(i) $4\text{FeCr}_2\text{O}_4 + 8\text{Na}_2\text{CO}_3 + 7\text{O}_2 \longrightarrow$
(ii) $5\text{Fe}^{2+} + \text{MnO}_4^- + 8\text{H}^+ \longrightarrow$
(b) Explain why actinoid contraction is greater from element to element than lanthanoid cont...
(a) Why second ionization enthalpies of chromium and copper are exceptionally higher than those of their neighbouring elements ?
(b) Why transition elements form interstitial compounds ?
(a) Complete and balance the following equations :
(i) $2\text{Na}_2\text{CrO}_4 + 2\text{H}^+ \longrightarrow$
(ii) $5\text{S}^{2-} + 2\text{MnO}_4^- + 16\text{H}^+ \longrightarrow$
(b) Why is chemistry of actinoids complicated as compared to lanthanoids ?
Which of the following transition metals does \textit{not} show variable oxidation states ?
(A) $\text{Ti}$
(B) $\text{Cu}$
(C) $\text{Mn}$
(D) $\text{Sc}$
(a) (i) What are transition elements ? Why do transition metals have high melting points and form coloured compounds ?
(ii) What is lanthanoid contraction ? Write two of its consequences.
(b) (i) Consider the following elements of 3d series : Sc Ti V Cr Mn Fe Co Ni Cu Zn
Answer the following :
(I) Which element shows the maximum number of oxidation states ?
(II) Which element is colourless in $+3$ oxidation state ?
(III) Which element is a strong reducing agent in $+2$ oxidation stat...
Which of the following is \textbf{not} a transition metal ?
(A) $\text{Hg}$
(B) $\text{Cu}$
(C) $\text{Ag}$
(D) $\text{Pt}$
Assertion (A) : Transition metals have high melting points.
Reason (R) : Transition metals have incompletely filled d-orbitals.
(a) (i) Define transition elements. Mention any two characteristics of transition elements.
(ii) How will you prepare $\text{KMnO}_4$ from pyrolusite ore ($\text{MnO}_2$) ?
OR
(b) (i) What is lanthanoid contraction ? What are the consequences (any two) of lanthanoid contraction ?
(ii) (I) Why does $...
Assertion (A) : Separation of $ ext{Zr}$ and $ ext{Hf}$ is difficult.\nReason (R) : $ ext{Zr}$ and $ ext{Hf}$ have almost identical atomic and ionic radii due to lanthanoid contraction.
Which of the following transition metals shows $+1$ and $+2$ oxidation states ?
(A) $ ext{Mn}$
(B) $ ext{Zn}$
(C) $ ext{Cu}$
(D) $ ext{Sc}$
Assertion (A) : Transition metals show their highest oxidation state with oxygen.\nReason (R) : The ability of oxygen to form multiple bonds to metals.
31. (a) (i) Account for the following :
(I) $\text{MnO}$ is basic while $\text{Mn}_2\text{O}_7$ is acidic.
(II) Iron has higher enthalpy of atomization than that of copper.
(III) $\text{Mn}^{3+}$ is a stronger oxidising agent than $\text{Cr}^{3+}$.
(ii) How do you prepare potassium dichromate from s...
Which property of transition metals enables them to form alloys ?
(A) High ionization enthalpy
(B) Similar atomic radii
(C) Catalytic property
(D) Complex formation
Which of the following transition metals shows $+1$ and $+2$ oxidation states ?
(A) $\text{Zn}$
(B) $\text{Cu}$
(C) $\text{Fe}$
(D) $\text{Cr}$
Assertion (A) : Highest oxidation state of $ ext{Mn}$ is $+7$ in first series of transition elements.
Reason (R) : Transition metals exhibit variable oxidation states.
32. (a) (i) (I) Why do transition metals show variable oxidation states ?
(II) Out of $\text{Mn}^{2+}$ and $\text{Ti}^{2+}$ which will be more paramagnetic and why ? $\text{[Atomic No. : Ti} = 22, \text{Mn} = 25\text{]}$
(III) Which ion is the strongest oxidising agent in the options given below :
$...
Assertion (A) : Highest oxidation state of $\text{Mn}$ is $+7$ in first series of transition elements.\nReason (R) : Transition metals exhibit variable oxidation states.
(a) (i) (I) Why do transition metals show variable oxidation states ?
(II) Out of $ ext{Mn}^{2+}$ and $ ext{Ti}^{2+}$ which will be more paramagnetic and why ? [Atomic No. : $ ext{Ti} = 22, ext{Mn} = 25$]
(III) Which ion is the strongest oxidising agent in the options given below :
$ ext{Cr}^{3+}, ...
Assertion (A) : Highest oxidation state of Mn is $+7$ in first series of transition elements.
Reason (R) : Transition metals exhibit variable oxidation states.
(a) (i) (I) Why do transition metals show variable oxidation states ?
(b) (i) What is meant by lanthanoid contraction ?
(ii) Why do transition metals form coloured compounds ?
(iii) Why are $E^{\circ}_{\text{M}^{2+}/\text{M}}$ values for Mn and Zn more negative than expected ?
(iv) Which is the most stable oxidation state of Cu and why ?
(v) Why is $\text{Ce}^{4+}$ in...
(a) (i) Why do $ ext{Zr}$ and $ ext{Hf}$ exhibit similar properties ?
(ii) "$E^{\circ}$ for $ ext{Mn}^{3+}/ ext{Mn}^{2+}$ couple is more positive than that for $ ext{Fe}^{3+}/ ext{Fe}^{2+}$." Justify the statement.
[Atomic number : $ ext{Mn} = 25$, $ ext{Fe} = 26$]
OR
(b) (i) Which element in 3d ser...
(b) (i) Why is $\text{Zn}$ a non-transition element ?
(b) (ii) Why do transition metals have high $\Delta_{\text{a}} \text{H}^{\circ}$ ?
(b) (ii) Why do transition metals have high $\Delta_a \text{H}^{\circ}$ ?
(b) (ii) Why do transition metals have high $\Delta_{\text{a}}H^{\circ}$ ?
The name inner transition metals is often used to refer to the
A. lanthanoids
B. actinoids
C. both lanthanoids and actinoids
D. d block elements
Arrange the products obtained in the following cases in the increasing order of their pKa values:
A. Oxidation of ethanol in presence of acidified potassium dichromate
B. Reaction of propanoic acid with $ ext{Br}_2$ in the presence of red Phosphorus
C. Reaction of isopropyl magnesium bromide with c...
Which of the following transition metals shows maximum number of oxidation states ?
(A) $\text{Mn}$
(B) $\text{Ti}$
(C) $\text{Sc}$
(D) $\text{Cu}$
The most common and stable oxidation state of lanthanoids is :
(A) $+ 4$
(B) $+ 2$
(C) $+ 3$
(D) $+ 6$
(a) (i) Account for the following :
(I) Transition metals form complex compounds 1
(II) $\text{Cr}^{2+}$ is strongly reducing while $\text{Mn}^{3+}$ is strongly oxidizing when both have $\text{d}^4$ configuration. 1
(III) The highest oxidation state is exhibited in oxoanions of a metal. 1
(ii) Write...
Which of the following transition metals does not show variable oxidation states ?
(A) $ ext{Cu}$
(B) $ ext{Sc}$
(C) $ ext{Ti}$
(D) $ ext{Fe}$
Assertion (A) : Zinc is not regarded as a transition element.
Reason (R) : Zinc has completely filled $3\text{d}$ orbitals in its ground state as well as in its oxidised state.
(B) (i) Write the preparation of $ ext{Na}_2 ext{Cr}_2 ext{O}_7$ from $ ext{FeCr}_2 ext{O}_4$.
(ii) What is Lanthanoid contraction ? Write its two consequences.
(iii) Name two elements of 3d series which show anomalous electronic configuration.
Out of the following statements, the incorrect statement is :
(A) La is actually an element of transition series.
(B) Zr and Hf have almost identical atomic radii because of lanthanoid contraction.
(C) Ionic radius decreases from $\text{La}^{3+}$ to $\text{Lu}^{3+}$ ion.
(D) Lanthanoids are radioact...
Out of the following statements, the \textit{incorrect} statement is :
(A) La is actually an element of transition series.
(B) Zr and Hf have almost identical atomic radii because of lanthanoid contraction.
(C) Ionic radius decreases from $\text{La}^{3+}$ to $\text{Lu}^{3+}$ ion.
(D) Lanthanoids are...
Out of the following statements, the correct statement is :
(A) $\text{La}$ is actually not an element of transition series.
(B) $\text{Zr}$ and $\text{Hf}$ have almost identical atomic radii.
(C) Lanthanoids are radioactive.
(D) Ionic radius increases from $\text{La}^{3+}$ to $\text{Lu}^{3+}$.
Which of the following properties of transition metals enables them to behave as catalysts ?
(A) High melting point
(B) High ionisation enthalpy
(C) Alloy formation
(D) Variable oxidation states
(a) (ii) Give reasons :
(I) $\text{Ce}^{4+}$ in aqueous solution is a good oxidising agent.
(II) The actinoid contraction is greater from element to element than lanthanoid contraction.
(III) $E^{\circ}_{\text{Zn}^{2+}/\text{Zn}}$ value is more negative than expected, whereas $E^{\circ}_{\text{Cu}^{...
(ii) Give reasons for the following :
(I) Transition metals exhibit catalytic properties.
(II) Transition metals have high enthalpy of atomisation.
(III) $ ext{Sc}$ is a transition element, while $ ext{Zn}$ is not.
32. (a) (i) Account for the following :
(I) Orange colour of $\text{Cr}_2\text{O}_7^{2-}$ ion changes to yellow when treated with an alkali.
(II) $\text{Zn}$, $\text{Cd}$ and $\text{Hg}$ are non-transition elements.
(III) $E^{\circ}$ value for $\text{Mn}^{3+}/\text{Mn}^{2+}$ couple is highly positiv...
Which of the following does not show variable oxidation state ?
(A) $\text{Sc}$
(B) $\text{Mn}$
(C) $\text{Cr}$
(D) $\text{Cu}$
Assertion (A) : Actinoids show wide range of oxidation states.
Reason (R) : This is due to comparable energies of 5f, 6d and 7s orbitals.
(a) (i) Account for the following :
(I) Orange colour of $\text{Cr}_2\text{O}_7^{2-}$ ion changes to yellow when treated with an alkali.
(II) $\text{Zn}$, $\text{Cd}$ and $\text{Hg}$ are non-transition elements.
(III) $E^{\circ}$ value for $\text{Mn}^{3+}/\text{Mn}^{2+}$ couple is highly positive ($...
Which of the following transition metals has the highest melting point ?
(A) $\text{Sc}$
(B) $\text{Cr}$
(C) $\text{Mn}$
(D) $\text{Zn}$
Assertion ($A$) : Actinoid contraction is greater from element to element than lanthanoid contraction.
Reason ($R$) : Actinoids show wide range of oxidation states.
(a) (i) Account for the following :
(I) Orange colour of $ ext{Cr}_2 ext{O}_7^{2-}$ ion changes to yellow when treated with an alkali.
(II) $ ext{Zn}$, $ ext{Cd}$ and $ ext{Hg}$ are non-transition elements.
(III) $E^\circ$ value for $ ext{Mn}^{3+}/ ext{Mn}^{2+}$ couple is highly positive ($+1\cdot57...
Which of the following transition metal ion is not coloured ?
(A) $\text{Cu}^{+}$
(B) $\text{Ni}^{2+}$
(C) $\text{Co}^{2+}$
(D) $\text{V}^{3+}$
Assertion ($A$) : Actinoids show irregularities in their electronic configurations.
Reason ($R$) : Actinoids are radioactive in nature.
OR
(b) Answer the following questions : $5\times1=5$
(i) Name two elements of 3d series for which the third ionisation enthalpies are quite high.
(ii) Out of $\text{KMnO}_4$ and $\text{K}_2\text{MnO}_4$, which one is paramagnetic and why ?
(iii) Write any one consequence of lanthanoid contraction.
...
Among the following outermost electronic configurations of transition metals, which one shows the highest oxidation state ?
(A) $3d^6 4s^2$
(B) $3d^5 4s^1$
(C) $3d^5 4s^2$
(D) $3d^3 4s^2$
Assertion (A) : Actinoids show irregularities in their electronic configurations.
Reason (R) : This is due to varying stability of $f^0$, $f^7$ and $f^{14}$ configurations.
With increase in atomic number, the melting point of transition metals :
(A) first increases and then decreases
(B) increases continuously
(C) first decreases and then increases
(D) remains constant
Assertion (A) : First ionisation enthalpy of Cr is lower than that of Zn.
Reason (R) : Zinc is a non-transition element.
(a) (i) Account for the following :
(I) The $\text{E}^\circ_{\text{Mn}^{2+}/\text{Mn}}$ value for manganese is highly negative, whereas $\text{E}^\circ_{\text{Mn}^{3+}/\text{Mn}^{2+}}$ is highly positive.
(II) Actinoids show wide range of oxidation states.
(III) Transition metals have high meltin...
Answer the following questions :
(i) Name two elements of $3\text{d}$ series for which the third ionisation enthalpies are quite high.
(ii) Out of $\text{KMnO}_4$ and $\text{K}_2\text{MnO}_4$, which one is paramagnetic and why ?
(iii) Write any one consequence of lanthanoid contraction.
(iv) How do ...
(b) (i) Complete and balance the following chemical equations :
(I) $\text{Cr}_2\text{O}_7^{2-}(\text{aq}) + \text{H}_2\text{S}(\text{g}) + \text{H}^+ \longrightarrow$
(II) $\text{Cu}^{2+}(\text{aq}) + \text{I}^-(\text{aq}) \longrightarrow$
(ii) Give reasons :
(I) Separation of mixture of lanthanoid...
Assertion (A) : Actinoids show wide range of oxidation states.
Reason (R) : Due to comparable energies of $5 ext{f}$, $6 ext{d}$ and $7 ext{s}$ orbitals.
(a) (i) Write the chemical equations involved in the preparation of potassium permanganate from pyrolusite ore ($ ext{MnO}_2$).
(ii) Give reasons for the following :
(I) $ ext{Sc}$ (Atomic No. 21) salts are white.
(II) $E^\circ_{ ext{Cu}^{2+}| ext{Cu}}$ is positive whereas $E^\circ_{ ext{Mn}^{2+}| e...
Out of the following transition elements, the maximum number of oxidation states is shown by
(A) Sc
(B) Cr
(C) Mn
(D) Fe
Which property of transition metals enables them to behave as catalysts ?
(A) Variable oxidation states
(B) Alloy formation
(C) High ionisation enthalpy
(D) High melting point
Attempt any five of the following: (a) Out of $\text{Cr}^{3+}$ and $\text{Mn}^{3+}$, which one is a strong oxidising agent and why? (b) Which ion amongst the following is colourless and why? $\text{Ti}^{4+}, \text{Cr}^{3+}, \text{V}^{3+}$ (Atomic number : $\text{Ti} = 22, \text{Cr} = 24, \text{V} = ...
Which of the following does not show variable oxidation states?
(A) Fe
(B) Cu
(C) Mn
(D) Sc
Transition elements form alloys easily because they have :
(A) same electronic configuration
(B) same enthalpies of atomisation
(C) same oxidation states
(D) nearly the same atomic size
Which of the following elements of 3d series of transition elements has the lowest $\Delta_a\text{H}^\circ$ ?
(A) Sc
(B) Cr
(C) Cu
(D) Zn
(c) Actinoid contraction is greater from element to element than lanthanoid contraction. Why ?
(f) Transition metals and their compounds are good catalysts. Justify.
(g) Scandium forms no coloured ions, yet it is regarded as a transition element. Why ?
Attempt any five of the following:
(a) Cu$^{+}$ is not stable in aqueous solution. Comment.
(b) Out of Cr$^{2+}$ and Fe$^{2+}$, which one is a stronger reducing agent and why?
(c) Actinoid contraction is greater from element to element than lanthanoid contraction. Why?
(d) KMnO$_{4}$ acts as an ...
Attempt any five of the following : (a) $\text{Cu}^+$ is not stable in aqueous solution. Comment. (b) Out of $\text{Cr}^{2+}$ and $\text{Fe}^{2+}$, which one is a stronger reducing agent and why ? (c) Actinoid contraction is greater from element to element than lanthanoid contraction. Why ? (d) $\te...
Which of the following oxidation state is common for all lanthanoids ?
(A) + 2
(B) + 4
(C) + 6
(D) + 3
OR (b) (i) Account for the following : (1) $\text{Cu}^{2+}$ salts are coloured while $\text{Zn}^{2+}$ salts are white. (2) $\text{Mn}^{3+}$ is a strong oxidising agent. (3) Transition metals and their many compounds act as good catalysts. (ii) What is lanthanoid contraction? Write one consequence of...
Which of the following characteristics of transition metals is associated with their catalytic activity?
(a) Paramagnetic nature
(b) Colour of hydrated ions
(c) High enthalpy of atomisation
(d) Variable oxidation states
Assertion (A) : Copper is a non-transition element.
Reason (R) : Copper has completely filled d-orbitals in its ground state.
Lanthanoid contraction is due to increase in :
(a) atomic number
(b) shielding by 4f electrons
(c) effective nuclear charge
(d) atomic radius
(a) (i) In 3d series, which transition element has positive $E^\circ_{\text{M}^{2+}/\text{M}}$ value and why ?
(ii) Name a member of lanthanide series which is well-known to show +4 oxidation state.
(b) Give reason :
(i) The highest oxidation state is exhibited in oxoanions of transition metals.
(ii...
Match the properties with the elements of 3d series:
(i) lowest enthalpy of atomisation (p) Sc
(ii) shows maximum number of oxidation states (q) Mn
(iii) transition metal that does not form coloured compounds (r) Zn
(s) Ti
(a) (i) (r), (ii) (q), (iii) (p)
(b) (i) (r), (ii) (s), (iii) (p)
(c) (i) (p)...
Which of the following is not considered a transition element?
(a) Scandium (b) Silver (c) Vanadium (d) Zinc
Assertion (A) : Transition metals have high enthalpy of atomisation.
Reason (R) : Greater number of unpaired electrons in transition metals results in weak metallic bonding.
(a) (I) Account for the following : (i) $E^{\circ}$ value for $\text{Mn}^{3+}/ \text{Mn}^{2+}$ couple is much more positive than that for $\text{Cr}^{3+}/ \text{Cr}^{2+}$. (ii) $\text{Sc}^{3+}$ is colourless whereas $\text{Ti}^{3+}$ is coloured in an aqueous solution. (iii) Actinoids show wide range...
Which of the following transition metals shows $+ 1$ and $+ 2$ oxidation states ?
(a) Mn
(b) Zn
(c) Sc
(d) Cu
Assertion (A) : Transition metals show their highest oxidation state with oxygen.
Reason (R) : The ability of oxygen to form multiple bonds to metals.
Which of the following transition metals do not show variable oxidation states?
(a) Cu
(b) Ti
(c) Mn
(d) Sc
Among the following outermost configurations of transition metals which one shows the highest oxidation state ? (a) $3d^34s^2$ (b) $3d^54s^1$ (c) $3d^54s^2$ (d) $3d^64s^2$
Which of the following transition metals does not show variable oxidation state ? (a) $\text{Ti}$ (b) $\text{Cr}$ (c) $\text{Cu}$ (d) $\text{Sc}$
The ions of metals of Group 12 (Zn, Cd and Hg) have completely filled d orbitals and so they :
(a) behave like semiconductors
(b) are very high melting solids
(c) do not behave like transition metals
(d) behave like superconductors
(a) (i) Account for the following : (1) Zn$^{2+}$ salts are colourless while Ni$^{2+}$ salts are coloured. (2) Cr$^{2+}$ is a strong reducing agent. (3) Transition metals and their compounds show catalytic activities. (ii) Write the ionic equations for the oxidizing action of MnO$_{4}^{-}$ in acidic...
The interstitial compounds of transition metals are (a) softer (b) more ductile (c) harder (d) more metallic than the metal itself.
Assertion (A) : Manganese shows the highest oxidation state of $+7$ in 3d series. Reason (R): Transition metals show variable oxidation states.
(a) Why is chemistry of actinoids complicated as compared to lanthanoids ?
(b) Complete the following reaction and justify that it is a disproportionation reaction :
$3 \text{MnO}_4^{2-} + 4 \text{H}^+ \rightarrow \_\_\_\_ + \_\_\_\_ + 2 \text{H}_2\text{O}$.
(c) The given graph shows the trends in m...
(a) A transition element X has electronic configuration $[ ext{Ar}] 4 ext{s}^2 3 ext{d}^3$. Predict its likely oxidation states. (b) Complete the reaction mentioning all the products formed : $2 ext{ KMnO}_4 \xrightarrow{\Delta} $ (c) Account for the following : (i) In the 3d transition series, zinc...
OR (b) Compound A with molecular formula $(\text{C}_2\text{H}_6\text{O})$ on oxidation by PCC gives compound B, which on treatment with dilute alkali forms compound C which is a $\beta$-hydroxy aldehyde. B on oxidation by potassium permanganate forms C. Identify A, B, C and D and write all the chemi...
Assertion (A) : Zn, Cd and Hg are not regarded as transition elements.
Reason (R) : Zn, Cd and Hg do not have partially filled d-orbitals in their ground state or in any one of their common oxidation states.
Answer the following questions :
(a) The chemistry of the actinoids is more complex as compared to lanthanoids. Why?
(b) Why is $\text{E}^\circ$ for $\text{Mn}^{3+}/\text{Mn}^{2+}$ redox couple more positive?
(c) Why do transition metals form large numbers of complex compounds?
(d) How does acidifie...
OR Compound A with molecular formula $(\text{C}_2\text{H}_6\text{O})$ on oxidation by PCC gives compound B, which on treatment with dilute alkali forms compound C which is a $\beta$-hydroxy aldehyde. B on oxidation by potassium permanganate forms C. Identify A, B, C and D and write all the chemical ...
(a) (i) Account for the following : (1) $[ ext{Ti}( ext{H}_2 ext{O})_6]^{4+}$ is colourless. (2) $ ext{MnO}$ is basic while $ ext{Mn}_2 ext{O}_7$ is acidic. (3) Actinoids show a wide range of oxidation states. (ii) Write the preparation of $ ext{KMnO}_4$ from $ ext{MnO}_2$.
OR (b) (i) Define lanthanoid contraction. Write its two consequences. Why is actinoid contraction greater than lanthanoid contraction? (ii) Write the preparation of $ ext{Na}_2 ext{Cr}_2 ext{O}_7$ from chromite ore.
Assertion (A) : Zn, Cd and Hg are not regarded as transition elements.
Reason (R) : Zn, Cd and Hg have completely filled d orbitals ($d^{10}$) in their ground state as well as in their common oxidation state.
(a) Account for the following :
(i) Transition elements have higher enthalpies of atomisation.
(ii) Separation of a mixture of Lanthanoid elements is difficult.
(iii) The $\text{E}^{\circ}_{\text{M}^{2+}/\text{M}}$ value for copper is positive.
OR
(b) Define transition elements. Which of the d-block...
(a) Account for the following : (i) Transition metals and their compounds act as good catalysts. (ii) $\text{Eu}^{2+}$ is a strong reducing agent. (iii) Chromium is hard whereas Zinc is soft metal. OR (b) What is Lanthanoid contraction ? Write two consequences of Lanthanoid contraction.
Account for the following :
(i) Zr and Hf have almost similar atomic radii.
(ii) Transition metals show variable oxidation states.
(iii) Zinc has lowest enthalpy of atomisation.
Why transition metals and their compounds act as good catalyst? How is the variability in oxidation states of transition metals different from that of the non-transition metals? Illustrate with examples.
From the given $E^{\ominus}_{M^{2+}/M}$ values of the first row transition elements, answer the following questions : (i) Why is $E^{\ominus}_{Mn^{2+}/Mn}$ value highly negative as compared to other elements? (ii) What is the reason for the irregularity in the above $E^{\ominus}$ values? (iii) Why i...
From the given $E^{\ominus}$ values of the first row transition elements, answer the following questions :
(i) Why is $E^{\ominus}_{\text{Mn}^{2+}/\text{Mn}}$ value highly negative as compared to other elements ?
(ii) What is the reason for the irregularity in the above $E^{\ominus}$ values ?
(iii) ...
35. Answer the following:
a. Why are all copper halides known except that copper iodide?
b. Why is the $E^0_{(V^{3+}/V^{2+})}$ value for vanadium comparatively low?
c. Why HCl should not be used for potassium permanganate titrations?
Account for the following : (i) Transition metals and their compounds show catalytic activities. (ii) Zn, Cd and Hg are non-transition elements. (iii) Zr and Hf are of almost identical atomic radii.
From the given $E^{\ominus}_{ ext{M}^{2+}/ ext{M}}$ values of the first row transition elements, answer the following questions : (i) Why is $E^{\ominus}_{ ext{Mn}^{2+}/ ext{Mn}}$ value highly negative as compared to other elements ? (ii) What is the reason for the irregularity in the above $E^{\omi...
Account for the following : (i) $\text{Cu}^{2+}$ salts are coloured while $\text{Zn}^{2+}$ salts are white. (ii) $E^\circ$ value for the $\text{Mn}^{3+}/\text{Mn}^{2+}$ couple is much more positive than that for $\text{Cr}^{3+}/\text{Cr}^{2+}$. (iii) Transition metals form alloys.
Define transition metals. Why $ ext{Zn}$, $ ext{Cd}$ and $ ext{Hg}$ are not called transition metals ? How is the variability in oxidation states of transition metals different from that of p-block elements ?
What is Lanthanoid contraction ? What is the cause of Lanthanoid contraction ? Write two consequences of Lanthanoid contraction.
(i) Why are melting points of transition metals high? (ii) Why the transition metals generally form coloured compounds? (iii) Why $E^\circ$ value for $ ext{Mn}^{3+}/ ext{Mn}^{2+}$ couple is highly positive?
Define transition metals. Why $Zn, Cd$ and $Hg$ are not called transition metals ? How is the variability in oxidation states of transition metals different from that of p-block elements ?
(iii) Why are enthalpies of atomisation of transition metals quite high ?
(a) (i) Silver atom has completely filled d-orbitals in its ground state, it is still considered to be a transition element. Justify the statement. (ii) Why are $E^{\ominus}_{M^{2+}/M}$ values of Mn and Zn more negative than expected ? (iii) Why do transition metals form alloys ?
(b) Answer the following questions on the basis of the figure given below :
(i) Which element in $3\text{d}$ series has lowest enthalpy of atomisation ?
(ii) Why do metals of the second and third series have greater enthalpies of atomisation ?
(iii) Why are enthalpies of atomisation of transition me...
Answer the following questions on the basis of the figure given below :
(i) Which element in 3d series has lowest enthalpy of atomisation ?
(ii) Why do metals of the second and third series have greater enthalpies of atomisation ?
(iii) Why are enthalpies of atomisation of transition metals quite hi...
Give reasons for the following statements : (a) Copper does not displace hydrogen from acids. (b) Transition metals and most of their compounds show paramagnetic behaviour. (c) Zn, Cd and Hg are soft metals.
Give reasons for the following statements:
(a) Scandium (Z=21) is a transition element but Zn (Z=30) is not.
(b) [Ti (H$_2$O)$_6$]$^{3+}$ is coloured while [Sc (H$_2$O)$_6$]$^{3+}$ is colourless.
(c) Physical and chemical properties of the 4d and 5d series of the transition elements are quite simila...
(a) Write any two consequences of Lanthanoid Contraction.
(b) Name the element of $3 ext{d}$ series which exhibits the largest number of oxidation states. Give reason.
Give reasons for the following statements : (a) Transition elements and their compounds act as good catalysts. (b) $E^{\circ}_{(\text{Mn}^{2+}/\text{Mn})}$ value is highly negative as compared to other elements. (c) $\text{Cr}^{2+}$ is a strong reducing agent.
OR (b) (i) The electronic configuration of Ce is : $_{58}\text{Ce} = [\text{Xe}]^{54} 4f^1 5d^1 6s^2$. Calculate the spin only magnetic moment of $\text{Ce}^{3+}$ ion. (ii) Why is copper regarded as a transition element although copper atom has completely filled d-orbitals in its ground state ? (iii...
Account for the following :
(a) Transition elements show variable oxidation states.
(b) $E^\circ_{\text{Cu}^{2+}/\text{Cu}}$ value for copper is highly positive.
(c) $\text{Cr}^{2+}$ is a strong reducing agent.
OR
What is Lanthanoid contraction ? Write its two consequences.
Account for the following :
(i) Transition metals generally form coloured compounds.
(ii) Zn has the lowest enthalpy of atomisation.
(iii) Atomic radii of 5d and 4d series of elements are almost identical.
(i) Which metal in the first series of transition metals exhibits +1 oxidation state most frequently and why ? (ii) Of the $d^4$ species, $ ext{Cr}^{2+}$ is strongly reducing while $ ext{Mn}^{3+}$ is strongly oxidising, why ? (iii) Name a transition element in 3d series (I) which does not exhibit va...
Define transition elements. Why do transition metals have higher enthalpies of atomisation? Which element in 3d series has lowest enthalpy of atomisation and why?