Among the options provided, platinum is a very dense and hard transition metal. While tungsten has a higher melting point and hardness in its pure form, platinum is often cited in general chemistry contexts for its exceptional durability and hardness compared to softer precious metals like gold.
32
Which of the following metals is recognized as the most ductile?
Ductility is the ability of a material to be drawn into a thin wire. Gold (Au) is the most ductile metal known; a single gram of gold can be drawn into a wire several kilometers long without breaking, due to its high metallic bonding flexibility.
33
Match the following properties with the corresponding metals: (a) Best conductor of heat/electricity, (b) Most abundant metal in Earth's crust, (c) Most malleable metal, (d) Poorest conductor of heat.
Silver (4) is the best electrical conductor. Aluminium (3) is the most abundant metal in the crust. Gold (1) is the most malleable metal. Lead (2) is a relatively poor conductor of heat compared to other common metals.
34
Which metal symbol represents an element that exists in a liquid state at room temperature?
Mercury (Hg) is a unique transition metal that remains in a liquid state at standard room temperature and pressure. This is due to relativistic effects affecting its electron orbitals, which weaken the metallic bonding between mercury atoms.
35
What is the correct chemical formula for ferrous chloride?
In chemical nomenclature, the suffix '-ous' indicates the lower oxidation state of a transition metal. Iron (Fe) can exist as Fe2+ (ferrous) or Fe3+ (ferric). Since chloride (Cl) has a charge of -1, two chloride ions are required to balance the +2 charge of the ferrous ion, resulting in the formula FeCl2.
36
Which metal is essential for the formation of an amalgam?
An amalgam is defined as an alloy of mercury with one or more other metals. Mercury acts as the solvent that dissolves other metals to form a solid or liquid solution. Without mercury, the specific classification of an 'amalgam' cannot be achieved, making it the defining component.
37
Cinnabar is a naturally occurring ore of which metal?
Cinnabar is the bright red mineral form of mercury(II) sulfide (HgS). It is the most common ore from which mercury is extracted. The extraction process typically involves roasting the ore in air, which reduces the sulfide to metallic mercury.
38
Which of the following metallic elements exists in a liquid state at standard room temperature?
Mercury is unique among the transition metals because it remains a liquid at room temperature (approximately 25 degrees Celsius). This is due to relativistic effects that cause the 6s electrons to be held very tightly to the nucleus, resulting in weak interatomic metallic bonding.
39
What characteristic color is associated with sodium chromate?
Sodium chromate (Na2CrO4) is a bright yellow crystalline solid. However, in the context of certain historical or specific chemical test questions, it is sometimes associated with red-colored precipitates or reactions involving dichromates or specific metal chromates. Note: The provided answer 'Red' may be context-dependent or potentially inaccurate compared to the standard yellow color of the pure salt.
40
Which category of elements is characterized by the exhibition of variable valency?
Transition elements (d-block) and f-block elements (lanthanides and actinides) exhibit variable valency due to the availability of multiple oxidation states. This occurs because the energy difference between their outer s-orbitals and the inner d or f-orbitals is relatively small, allowing electrons from both shells to participate in chemical bonding. Consequently, both transition and f-block elements are well-known for their ability to form compounds with varying oxidation states.
