Download App

Chemistry 1 Marks Question

d-and f-Block Elements · Rajasthan Board (RBSE) STD 12 Science (Rajasthan - English Medium). 15 questions.

Questions

1 Marks Question

Take a timed test

15 questions · self-marked practice — reveal the answer and mark yourself.

Question 11 Mark
In what way is the electronic configuration of the transition elements different from that of the non-transition elements?
Answer
In transition elements, the penultimate shell is partially filled. In non-transition elements, first the inner shells are filled and then the last shell is filled.
View full question & answer→
Question 21 Mark
What is meant by 'disproportionation'? Give two examples of disproportionation reaction in aqueous solution.
Answer
(i) $MnO _4^{2-}+4 H ^{+} \longrightarrow 2 MnO _4^{-}+ MnO _2+2 H _2 O$,
(ii) $3 CrO _4^{3-}+8 H ^{+} \longrightarrow 2 CrO _4^{2-}+ Cr ^{3+}+4 H _2 O$.
View full question & answer→
Question 31 Mark
Why are $Mn ^{2+}$ compounds more stable than $Fe ^{2+}$ towards oxidation to their +3 state?
Answer
$Mn ^{2+}$ has stable electronic configuration ([Ar] $4 s^0, 3 d^5$ ) and thus does not easily change to $Mn ^{3+} . Fe ^{2+}\left[[ Ar ] 4 s^0, 3 d^6\right]$ on oxidation forms $Fe ^{3+}$ [Ar] $4 s^0, 3 d^5$ ] a more stable configuration.
View full question & answer→
Question 41 Mark
Which metal in the first series of transition metal exhibits +1 oxidation state most frequently and why?
Answer
Copper because it will achieve a completely filled $d$-orbital and a stable configuration on losing an electron.
View full question & answer→
Question 51 Mark
Give reason and select one atom/ion which will exhibit asked property :
(i) $Sc ^{3+}{\text { or } Cr ^{3+}}^{3+}$ (Exhibit diamagnetic behaviour)
(ii) Cr or Cu (High melting and boiling point)
Answer
(i) $Sc ^{3+}$, because of absence of unpaired electron.
(ii) Cr, because of presence of stronger intermetallic bonding than Cu .
View full question & answer→
Question 61 Mark
When $MnO _2$ is fused with KOH in presence of $KNO _3$ as an oxidizing agent, it gives a dark green compound (A). Compound (A) disproportionate in acidic solution to give purple compound (B). An alkaline solution of compound (B) oxidises KI to compound (C) whereas an acidified solution of compound (B) oxidises KI to (D). Identify (A), (B), (C) and (D).
Answer
(A) $K _2 MnO _4$ green, (B) $KMnO _4$ purple, (C) $Mn _2 O _3$, (D) $Mn _2 O _4$.
View full question & answer→
Question 71 Mark
Complete and balance the following chemical equations :
(i) $F e ^{ 2 + }+ M n O _4^{-}+ H ^{+} \rightarrow$
(ii) $MnO _4^{-}+ H _2 O + I ^{-} \rightarrow$
Answer
(i) $5 Fe ^{2+}+ MnO _4^{-}+8 H ^{+} \rightarrow Mn ^{2+}+4 H _2 O +5 Fe ^{3+}$
(ii) $2 MnO _4^{-}+ H _2 O + I ^{-} \rightarrow 2 MnO ^2+2 OH ^{-}+ IO _3^{-}$
View full question & answer→
Question 81 Mark
Write electronic configuration of the following elements:
(i) V (Z=23)
(ii) Zn (Z=30)
Answer
(i) ${ }_{23} V \longrightarrow 1 s^2, 2 s^2 2 p^6, 3 s^2 3 p^6 3 d^3, 4 s^2$
(ii) $30 Zn \longrightarrow 1 s^2, 2 s^2 2 p^6, 3 s^2 3 p^6 3 d^{10}, 4 s^2$
View full question & answer→
Question 91 Mark
What are interstitial compounds? Why are such compounds well known for transition metals?
Answer
Interstitial compounds are formed when small non-metallic atoms like H and C are trapped inside the crystal lattice of metals.
View full question & answer→
Question 101 Mark
Why is separation of lanthanoid elements difficult?
Answer
The separation of lanthanoid elements is difficult because of lanthanoid contraction. Due to contraction the change in atomic and ionic radii is very small and these elements show similar chemical properties and the separation becomes difficult.
View full question & answer→
Question 111 Mark
Explain why iron (Fe) is a transition metal, but sodium is not?
Answer
Iron is a d-block element and shows properties of transition metals like variable valancy, coloured ion, complex formation etc. Sodium is a s-block element. It does not show the properties of transition metal.
View full question & answer→
Question 121 Mark
Why is $ Cu^{+} $ diamagnetic whereas $ Cu^{2+} $ is paramagnetic?
Answer
$ Cu^{+} $ has configuration [Ar] $ 3d^{10} $ whereas $ Cu^{2+} $ has [Ar] $ 3d^{9} $. It is thus evident that $ Cu^{+} $ has no unpaired electron and thus diamagnetic. $ Cu^{2+} $ has one unpaired electron in 3d sub-shell and thus paramagnetic.
View full question & answer→
Question 131 Mark
What are transition metals? Which d-block elements are not normally considered as transition metals?
Answer
Transition metals are those elements which have incomplete d-orbital and the last electron enters the (n-1)d orbital. Zn, Cd, Hg are not consider as transition metals.
View full question & answer→
Question 141 Mark
Explain giving reason:
(a) Transition metals and many of their compounds show paramagnetic behaviour.
(b) The enthalpies of atomisation of the transition metals are high.
(c) Transition metals in their many compounds act as good catalyst.
Answer
(a) Due to the presence of unpaired electrons.
(b) Due to strong inter-atomic forces.
(c) Due to variable oxidation states.
View full question & answer→
Question 151 Mark
Any transition series contains only ten elements, why?
Answer
It is because there are only 10 members since in the period left to right atomic number increases and hence after a certain number when the d subshell is fully filled the electron has to go in the s and p-subshell and hence it (d-block) ends up with only 10 elements.
View full question & answer→
Generate Paper FreeAll d-and f-Block Elements topics