Brass is an alloy primarily composed of copper and zinc, which provides it with a bright gold-like appearance. Bronze is an alloy primarily composed of copper and tin, which makes it harder and more resistant to corrosion than pure copper.
62
How is an alloy classified in terms of chemical mixture types?
An alloy is a solid solution of two or more elements, where at least one is a metal. Because the components are uniformly distributed at the atomic level, an alloy is classified as a homogeneous mixture rather than a chemical compound.
63
Evaluate the following statements regarding the properties of metals: 1. Mercury is liquid at room temperature. 2. Malleability is the ability to be beaten into thin sheets. 3. Ductility is the ability to be drawn into wires. Which statements are correct?
All three statements are accurate descriptions of metallic properties. Mercury is indeed the only metal that is liquid at standard room temperature. Malleability refers to the physical property of metals to deform under compressive stress into thin sheets, and ductility refers to the ability to be stretched into thin wires under tensile stress.
64
Which statement accurately describes the electronic structure of transition elements?
Transition elements are defined by the filling of d-orbitals. According to the general electronic configuration (n-1)d^1-10 ns^1-2, both the outermost shell (ns) and the penultimate shell ((n-1)d) are involved in bonding and are considered incomplete, which is a hallmark of transition metal chemistry.
65
Which of the following common alloys is composed of tin?
Solder is a fusible metal alloy used to join metal workpieces together. It is typically composed of tin and lead, though lead-free versions exist. Brass contains zinc, duralumin contains aluminium, and steel is primarily iron and carbon.
66
What are the decomposition products when hydrated ferrous sulphate crystals are heated in a test tube?
When hydrated ferrous sulphate (FeSO4·7H2O) is heated, it first loses its water of crystallization. Upon further heating, it decomposes into ferric oxide (Fe2O3), sulphur dioxide (SO2), and sulphur trioxide (SO3). The water is released as steam. The balanced chemical equation is 2FeSO4·7H2O(s) → Fe2O3(s) + SO2(g) + SO3(g) + 14H2O(g).
67
Why is the alloy known as 'German silver' given that specific name?
Despite its name, German silver contains no actual silver. It is an alloy composed of copper, zinc, and nickel. It is named 'German silver' primarily because of its silvery-white, lustrous appearance, which resembles metallic silver, making it popular for decorative items and ornaments.
68
Which of the following metals is found in a liquid state at standard room temperature?
Mercury is the only elemental metal that is liquid at standard room temperature and pressure. Its unique behavior is attributed to the relativistic contraction of its 6s orbitals, which leads to weak metallic bonding and a low melting point of approximately -38.8 degrees Celsius.
69
Which of the following elements is known for being relatively soft and flexible in its metallic state?
Copper is a transition metal that exhibits high ductility and malleability, allowing it to be easily shaped into wires or sheets. In contrast, sulphur, carbon (in non-metallic forms), and phosphorus are non-metals that are typically brittle or exist in molecular forms that lack metallic flexibility.
70
What is the standard melting point of tungsten in degrees Celsius?
Tungsten is a transition metal known for having the highest melting point of all pure metals. Its melting point is approximately 3,380°C (6,116°F), which makes it ideal for high-temperature applications such as incandescent light bulb filaments and aerospace components.
