Free Electronic Structure of d-Block Elements MCQs with Answers

• A. lies between groups II and III of the periodic table
• B. forms at least one stable ion with a partially filled d subshell
• C. has a full d subshell
• D. is a hard metal with a high melting point

Explanation: The definition rests on the partially filled d subshell in the element or in one of its ions, because that is what produces variable…

• A. [Ar] 3d4 4s2
• B. [Ar] 3d6
• C. [Ar] 3d5 4s1
• D. [Ar] 4s2 4p4

Explanation: One 4s electron is promoted so that both the 3d and 4s subshells are exactly half filled, an arrangement of extra stability arising from…

• A. the 3d subshell
• B. the 4p subshell
• C. the innermost shell
• D. the 4s subshell

Explanation: Although 4s fills before 3d, once the d subshell is occupied the 4s level becomes the higher in energy, so it is emptied first on…

• A. electrons move between d orbitals split by the ligands, absorbing part of the visible spectrum
• B. the metals reflect all wavelengths equally
• C. they contain water of crystallisation
• D. their ions are very large

Explanation: Ligands split the five d orbitals into groups of slightly different energy, and the small energy gap corresponds to visible light, so the…

• A. Variable oxidation states
• B. Formation of complex ions
• C. Catalytic activity
• D. Low melting points and softness

Explanation: Transition metals are hard, dense and high melting, because both the 3d and 4s electrons contribute to metallic bonding, and tungsten…

• A. their atomic radii vary greatly
• B. the 3d and 4s subshells are close in energy, so a variable number of electrons can be involved in bonding
• C. they always lose all their outer electrons
• D. they have unusually high electronegativity

Explanation: Because the energy gap between 4s and 3d is small, successive ionisation energies rise only gradually and several different numbers of…

• A. ligands, donating a lone pair of electrons to the central metal ion
• B. reducing agents
• C. counter ions balancing the charge
• D. solvent molecules with no bonding role

Explanation: A ligand is a species with at least one lone pair that forms a dative covalent bond to the central metal ion, and here each nitrogen…

• A. the charge on the complex ion
• B. the number of ligands in the solution
• C. the number of dative bonds formed between the ligands and the metal ion
• D. the oxidation state of the metal

Explanation: Coordination number counts the bonds to the central ion, so it is six in the octahedral hexaaquairon complex and four in the tetrahedral…

• A. their high density
• B. their ability to change oxidation state and to adsorb reactants onto their surface
• C. their low melting points
• D. the complete absence of d electrons

Explanation: Variable oxidation states allow a transition metal to accept and release electrons during a reaction, providing an alternative pathway of…

• A. Fe3+
• B. Cu2+
• C. Zn2+
• D. Ni2+

Explanation: The zinc ion has a completely filled 3d10 configuration, so no d to d electronic transition is possible and no visible light is absorbed.

• A. plus 2
• B. plus 4
• C. plus 7
• D. plus 6

Explanation: Manganese has five 3d and two 4s electrons, so all seven can be involved in bonding, giving the plus 7 state found in the permanganate…

• A. [Ar] 3d4 4s2
• B. [Ar] 3d6
• C. [Ar] 3d5 4s1
• D. [Ar] 3d8

Explanation: Neutral iron is [Ar] 3d6 4s2, and forming the two plus ion removes both 4s electrons because 4s lies above 3d once the d subshell is…

• A. their atoms are much larger
• B. they contain no free electrons
• C. both the d and s electrons take part in metallic bonding, giving a stronger and more compact lattice
• D. they are non metallic in character

Explanation: A larger number of delocalised electrons per atom means stronger attraction between the cations and the electron sea, so more energy is…

• A. it is not a metal
• B. it forms no compounds
• C. it has no d electrons at all
• D. its atom and its only ion both have a completely filled 3d subshell

Explanation: Zinc is 3d10 4s2 as the atom and 3d10 as the Zn2+ ion, so it never has a partly filled d subshell and consequently shows only one…

• A. the almost colourless manganese two ion
• B. manganese metal
• C. the green manganate six ion
• D. brown manganese dioxide

Explanation: In acidic solution permanganate is reduced from plus 7 to plus 2, and the sharp change from deep purple to almost colourless is what makes…

• A. paired electrons only
• B. unpaired electrons in the d orbitals
• C. an even number of protons
• D. delocalised pi bonds

Explanation: Unpaired electrons give the ion a magnetic moment, so the substance is drawn into a magnetic field and is described as paramagnetic, and…

• A. the metals react chemically to form a compound
• B. their atoms are of similar size and can substitute for one another in the lattice
• C. they have identical melting points
• D. they are all radioactive

Explanation: Atomic radii across a transition series change very little, since the added electrons enter an inner d subshell and shield the extra…

• A. increases sharply
• B. decreases sharply
• C. changes very little, because the added d electrons shield the increased nuclear charge well
• D. first increases then decreases sharply

Explanation: Each element adds a proton and a d electron, and because that electron enters an inner subshell it shields the outer 4s electrons…

• A. magnesium
• B. iron
• C. cobalt
• D. copper

Explanation: Each haem group holds an iron two ion coordinated to four nitrogen atoms of the porphyrin ring, with the remaining site available to bind…

• A. Haber process
• B. hydrogenation of vegetable oils
• C. Contact process for making sulphuric acid
• D. cracking of long chain alkanes

Explanation: Vanadium pentoxide catalyses the oxidation of sulphur dioxide to sulphur trioxide, working by being reduced and then reoxidised in a…