21. The term “ligand” in coordination chemistry refers to:

a) A type of bond
b) A molecule or ion that donates a pair of electrons to a metal
c) A type of oxidation state
d) A type of transition metal
Answer: b) A molecule or ion that donates a pair of electrons to a metal

22. The transition metal that is essential for the oxygen transport in blood is:

a) Zinc
b) Iron
c) Cobalt
d) Manganese
Answer: b) Iron

23. The process of forming a complex with a metal ion where the metal is surrounded by ligands is called:

a) Complexation
b) Precipitation
c) Hydrolysis
d) Oxidation
Answer: a) Complexation

24. The coordination number of a metal ion in a complex refers to:

a) The number of metal atoms
b) The number of ligands directly bonded to the metal
c) The total number of electrons in the metal
d) The number of oxidation states of the metal
Answer: b) The number of ligands directly bonded to the metal

25. Which of the following is NOT a common oxidation state of chromium?

a) +2
b) +3
c) +6
d) +5
Answer: d) +5

26. The transition metal used in the manufacture of stainless steel is:

a) Copper
b) Iron
c) Nickel
d) Zinc
Answer: c) Nickel

27. The element that forms a pink-colored complex with ammonia is:

a) Copper
b) Nickel
c) Cobalt
d) Iron
Answer: c) Cobalt

28. Which transition metal forms a tetrahedral complex with chloride ions?

a) Iron
b) Copper
c) Nickel
d) Cobalt
Answer: d) Cobalt

29. The ability of transition metals to form colored compounds is primarily due to:

a) The presence of unpaired electrons
b) The formation of metal-metal bonds
c) The presence of filled d-orbitals
d) The absence of inner electron shells
Answer: a) The presence of unpaired electrons

30. The element that is commonly used in electroplating processes is:

a) Gold
b) Silver
c) Platinum
d) Chromium
Answer: d) Chromium