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Published on: 28/11/2025
Download Tamil Nadu 12th Standard Chemistry question papers, model tests, one-mark questions, important questions, and public exam papers in PDF format. Free study materials and answer keys for TN State Board students.
Questions + Answers key
Take MCQ Chemistry Test
1.
Exactly half filled and completely filled f orbitals are present in _______.
La3+ and Lu3+
Gd3+ and Lu3+
Lu3+ and Gd3+
La3+ and Gd3+
2.
Ionisation enthalpy of Nickel is 2490 KJ mol-1 and that of platinum is 2655 KJ mol-1 hence which is more stable_______.
Ni+2
Pt2+
Same stability
None
3.
In chromyl chloride test, the yellow precipitate formed is _______.
CrO2Cl2
Na2CrO4
PbCrO4
KHSO4
4.
Which one of the following is not correct?
Along the lanthanide series covalent character increases
Basic character decreases from La3+ to Lu3+
Ionic size increases from La3+ to Lu3+
Reducing behaviour decreases from La3+ to Lu3+
5.
The most common oxidation state of lanthanoid is _______.
+2
+ 1
+ 3
+ 4
6.
Which ion shows a \(\mu\) of 5.91 BM?
Mn2+
Ti3+
Cr3+
Cu2+
7.
The colour of [Ti(H2O)6]3+ ion is due to _______.
d-d-transition
Presence of water molecules
Interatomic transfer of electrons
None of the above
8.
Choose the wrong statement regarding K2Cr2O7.
It is a powerful oxidizing agent.
It is used in tanning industry.
It is soluble in water.
It reduces ferric sulphate to ferrous sulphate.
9.
For the four successive transition elements (Cr, Mn, Fe & Co) the stability of +2 oxidation state will be there in which of the following one
Fe>Mn>Co>Cr
Co>Mn>Fe>Cr
Cr>Mn>Co>Fe
Mn>Fe>Cr>Co
10.
Which of the following ions of salt is white in colour?
Cd2+
Cu2+
Co3+
V3+
11.
Chromyl chloride when dissolved in NaOH solution gives yellow solution. The yellow solution contains _______.
\(\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}\)
\(\mathrm{CrO}_{4}^{2-}\)
\(\mathrm{CrO}_{5}\)
\(\mathrm{Cr}_{2} \mathrm{O}_{3}\)
12.
In the dichromate anion (Cr2O7)2- _______.
4 Cr - O bonds are equivalent
6 Cr - O bonds are equivalent
All Cr -O bonds are equivalent
All Cr - O bonds are non equivalent
13.
Which one of the following is not correct?
La(OH)3 is less basic than Lu(OH)3
In lanthanoid series ionic radius of Ln3+ ions decreases
La is actually an element of transition metal series rather than lanthanide series
Atomic radii of Zr and Hf are same because of lanthanide contract
14.
The actinoid elements which show the highest oxidation state of +7 are _______.
Np, Pu, Am
U, Fm, Th
U, Th, Md
Es, No, Lr
15.
The most common oxidation state of actinoids is _______.
+2
+3
+4
+6
16.
Which of the following oxidation states is most common among the lanthanoids?
+4
+2
+5
+3
17.
Which of the following lanthanoid ions is diamagnetic?
Eu2+
Yb2+
Ce2+
Sm2+
18.
Which one of the following statements related to lanthanons is incorrect?
Europium shows +2 oxidation state
The basicity decreases as the ionic radius decreases from Pr to Lu.
All the lanthanons are much more reactive than aluminium
Ce4+ solutions are widely used as oxidising agents in volumetric analysis.
19.
The number of moles of acidified KMnO4 required to oxidize 1 mole of ferrous oxalate(FeC2O4) is _______.
5
3
0.6
1.5
20.
21.
Permanganate ion changes to ________ in acidic medium.
MnO42−
Mn2+
Mn3+
MnO2
22.
Which of the following statements is not true?
on passing H2S, through acidified K2Cr2O7 solution, a milky colour is observed
Na2Cr2O7 is preferred over K2Cr2O7 in volumetric analysis
K2Cr2O7 solution in acidic medium is orange in colour
K2Cr2O7 solution becomes yellow on increasing the PH beyond 7
23.
24.
The correct order of increasing oxidizing power in the series _______.
VO2+ < Cr2O72- < MnO4-
Cr2O72- < VO2+ < MnO4-
Cr2O72- < MnO4- < VO2+
MnO4- < Cr2O72- < VO2+
25.
The catalytic behaviour of transition metals and their compounds is ascribed mainly due to _______.
their magnetic behaviour
their unfilled d orbitals
their ability to adopt variable oxidation states
their chemical reactivity
26.
The magnetic moment of Mn2+ ion is _______.
5.92BM
2.80BM
8.95BM
3.90BM
27.
Which one of the following ions has the same number of unpaired electrons as present in V3+?
Ti3+
Fe3+
Ni2+
Cr3+
28.
Among the transition metals of 3d series, the one that has highest negative \(\left( \frac { M^{ 2+ } }{ M } \right) \) standard electrode potential is _______.
Ti
Cu
Mn
Zn
29.
Which of the following d block element has half filled penultimate d sub shell as well as half filled valence sub shell?
Cr
Pd
Pt
none of these
30.
Sc (Z = 21) is a transition element but Zinc (z = 30) is not because _______.
both Sc3+ and Zn2+ ions are colourless and form white compounds
In case of Sc, 3d orbital are partially filled but in Zn these are completely filled
last electron as assumed to be added to 4s level in case of zinc
both Sc and Zn do not exhibit variable oxidation states
1.
(b)
Gd3+ and Lu3+
2.
(b)
Pt2+
3.
(c)
PbCrO4
4.
(c)
Ionic size increases from La3+ to Lu3+
5.
(c)
+ 3
6.
(a)
Mn2+
7.
(a)
d-d-transition
8.
(d)
It reduces ferric sulphate to ferrous sulphate.
9.
(d)
Mn>Fe>Cr>Co
10.
(a)
Cd2+
11.
(b)
\(\mathrm{CrO}_{4}^{2-}\)
12.
(b)
6 Cr - O bonds are equivalent
13.
(a)
La(OH)3 is less basic than Lu(OH)3
14.
(a)
Np, Pu, Am
15.
(b)
+3
16.
(d)
+3
17.
Yb2+ - 4f14 - no unpaired electrons - diamagnetic
18.
As we move from La to Lu, their metallic behaviour because almost similar to that of aluminium.
19.
+7 +2+3 2+ 3+ 4+
MnO4- + FeC2O4 ⟶ Mn2+ + Fe3+ + 2CO2
5e- acception 3e- release
5 moles of FeC2O4 \(\equiv\) 3 moles of KMnO4
1 mole of FeC2O4 \(\equiv\) (3/5) moles of KMnO4
1 mole of FeC2O4 \(\equiv\) 0.6 moles of KMnO4
20.
(c)
21.
MnO-4 + 8H+ + 5e- → Mn2+ + 4H2O
22.
(b)
Na2Cr2O7 is preferred over K2Cr2O7 in volumetric analysis
23.
(b)
24.
+5 +6 +7
VO2+ < Cr2O72- < MnO4-
Greater the oxidation state, higher is the oxidising power.
25.
(c)
their ability to adopt variable oxidation states
26.
Mn2+ ⇒ 3d5 contains 5 unpaired electrons
n = 5,
\( \sqrt{n(n+ 2)} \) BM
\(= \sqrt{5(5+ 2)} = \sqrt{35} = 5.92 BM\)
27.
(c)
Ni2+
28.
(a)
Ti
29.
Cr ⇒ [Ar]3d54s1
30.
(b)
In case of Sc, 3d orbital are partially filled but in Zn these are completely filled
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