The d and f Block Elements

Class 12th Chemistry – 8 The d and f Block Elements MCQs

The catalyst used for converting sulphur dioxide to sulphur trioxide is _______________ .

Correct! Wrong!

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Vanadium pentoxide is used as catalyst to convert sulphur dioxide to sulphur trioxide as follows: SO2 + V2O5 -------SO3 + V2O4. In the reaction, vanadium changes its oxidation state from +5 to +4.

A transition element that has no electron in the ns orbital belongs to the ____.

Correct! Wrong!

The element Pd palladium having atomic number 46 belongs to 2nd transition series. This has no electron in ns orbital. It has the electronic configuration [Kr] 4d10 5s0.

Lanthanoids are characterized by the filling up of ____ energy level.

Correct! Wrong!

Lanthanoids are characterized by filling up of antepenultimate 4f energy level.

Which of the following shows maximum magnetic moment?

Correct! Wrong!

Magnetic moment is inversely proportional to the number of unpaired electrons. The number of unpaired electrons is maximum in 3d5 as it has 5 unpaired electrons.

What is the product formed when lanthanoid is heated with sulphur?

Correct! Wrong!

Lanthanoid, when heated with sulphur, forms Ln2S3.

Balance the following reaction: Cr2+ I- + H+ ----Cr3+ + I2 + H2O

Correct! Wrong!

T he balanced reaction is Cr2+ 6I- + 14H+ ----2Cr3+ + 3I2 + 7H2O.

An element which shows +1 oxidation state most frequently is ____.

Correct! Wrong!

Copper has electronic configuration 3d10 4s1 as it can easily lose one electron to give stable 3d10 configuration.

Potassium permanganate is purple in colour because of ____ .

Correct! Wrong!

In potassium permanganate, the oxidation state of Mn is +7. So it cannot show d-d transition. The colour is due to charge transfer.

Which is an alloy?

Correct! Wrong!

Fe and C form an alloy called cementite Fe3C.

Zero oxidation is shown in Ni(CO)4due to ____.

Correct! Wrong!

Zero oxidation state is shown in forming metal carbonyls because π-electrons donated by the ligands are accepted into the empty d-orbitals.

The highest oxidation state shown by the transition element in 5d series is ____.

Correct! Wrong!

The elements which show the greatest number of oxidation state occur in or near the middle of the series. Thus, the highest oxidation state is +8 which is shown by Osmium in 5d series.

The high values of enthalpies of atomization may be attributed to ____.

Correct! Wrong!

The enthalpy of atomization can be defined as the change in enthalpy which involves breaking of the metallic lattice of the crystalline metal into atoms. Thus, the high values of enthalpies of atomization may be attributed to the strong metallic bonds that are present.

Lanthanoids show paramagnetism because of ____ .

Correct! Wrong!

Paramagnetism is shown by the positive ions of lanthanoids due to the presence of unpaired electrons in the incomplete 4f subshell.

The tendency of fluorine to stabilize the highest oxidation state is due to ________________ .

Correct! Wrong!

The tendency of fluorine to stabilize the highest oxidation state is due to either higher lattice enthalpy, as in the case of CoF3 or higher bond enthalpy due to higher covalent bonds, as in VF5 and CrF6.

Of the options given, __________ is not radioactive.

Correct! Wrong!

All actinoids are radioactive. Of the lanthanoids only Promethium is radioactive. Hence, of the options given, Samarium is not radioactive.

The colour of Cr2 in acidic medium is ____.

Correct! Wrong!

In acidic medium, the pH value is < 7 and so Cr2 has orange colour.

The electronic configuration of Cr [Z = 24] is ____.

Correct! Wrong!

In Cr, the energy difference between the 3d and 4s orbitals is not large enough to prevent the electrons entering the 3d orbitals. Thus, to acquire increased stability, one of the 4s electrons goes to nearby 3d orbitals so that 3d orbitals become half filled. Therefore, the electronic configuration of Cr is [Ar] 3d5 4s1.

Which of the following is not a characteristic property of the transition elements?

Correct! Wrong!

The elements belonging to the transition series are metallic in nature. Hence, they depict the characteristics of metals such as high melting point, high enthalpies of atomization, high boiling point, high thermal and electrical conductivity, metallic lustre etc.

The ionic radii of transition metals are smaller than those of representative elements belonging to the same period because ____ .

Correct! Wrong!

The ionic radii of transition metals are smaller than those of representative elements belonging to the same period because s and d-block elements form positive ions, whereas p-block mostly form negative ions.

______________ is not used in the manufacture of fuel rods for nuclear reactors?

Correct! Wrong!

Plutonium and uranium are radioactive and are used as fuel for fuel rods in nuclear reactors. Thorium is also used as a fuel for fuel rods as Th-232 absorbs a neutron to become Th-233 which undergoes series of decay to yield U-233.

Among the following, which of the orbital belongs to higher energy?

Correct! Wrong!

When the ions or molecules approach the metal ion, the five d-orbitals split into two sets: one set consisting of two d-orbital (dx2- y2 and dz2) of higher energy and the other set consisting of three d-orbitals (dxy, dyz and dzx) of lower energy.

Ruthenium belongs to ____.

Correct! Wrong!

The second transition series involves the elements from Y to Cd having the atomic numbers 39 to 48. Ruthenium having atomic number 44 belongs to 2nd transition series.

Copper has a positive Cu2+/Cu reduction potential value because _________________ .

Correct! Wrong!

Copper has a positive reduction potential electrode value because of high enthalpy of ionization and very low enthalpy of hydration.

On moving from Ac to Lr, the effective nuclear charge ____.

Correct! Wrong!

On moving down from Ac to Lr, the effective nuclear charge increases. This is due to imperfect shielding of one 5f electron by another in the same subshell.

________________ is used in the manufacture of vanaspati ghee.

Correct! Wrong!

Generally, finely divided nickel powder is used in hydrogenation of unsaturated organic compounds. Here, the unsaturated organic compound refers to vanaspati ghee.

On moving from Pu to Md, the size of the ions ____.

Correct! Wrong!

Due to poor shielding effect of the 5f electrons, the radii of the atom decreases across the series on moving from Pu to Md.

thanoids and actinoids are commonly known as ____.

Correct! Wrong!

Lanthanoids and actinoids are commonly known as Inner transition elements.

There is a slight increase in the atomic radii of Zn, Cd and Hg due to ____ .

Correct! Wrong!

Towards the end of the series, there are increased electron-electron repulsions between the added electrons in the same orbitals. This exceeds the attractive forces due to increased nuclear charge. Therefore, electron cloud expands and the size increases.

The number of moles of hydrogen peroxide required to decolorize 1 mole of potassium permanganate is ____.

Correct! Wrong!

2KMnO4 + 3H2SO4 + 5H2O2 ------K2SO4 + 2MnSO4 + 8H2O + 5O2. Thus, 2 moles of KMnO4 react with hydrogen peroxide = 5 mole therefore, 1 mole of KMnO4 react with hydrogen peroxide = 5/2 mole.

Which among the following is not a characteristic property of an alloy?

Correct! Wrong!

Conductivity is the characteristic property of interstitial compounds and not alloys.

Class 12th Chemistry - 8 The d and f Block Elements MCQs
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Class 12th Chemistry - 8 The d and f Block Elements MCQs