Chemistry of Metals and Alloys

Stainless steel is an alloy of iron, chromium, and other elements that does not contain copper. Other options like brass (copper+zinc), bronze (copper+tin), and German silver (copper+nickel+zinc) all contain copper.

Duralumin is a strong, lightweight alloy composed primarily of aluminium (about 95%), with copper (about 4%), magnesium (about 0.5%), and manganese. It was developed for aircraft construction and other applications requiring high strength-to-weight ratio. Bronze contains copper and tin, magnalium is aluminium-magnesium, and monel is nickel-copper.

Chromium has an atomic weight of approximately 52, while iron has an atomic weight of approximately 56. The other metals listed all have higher atomic weights: nickel (~59), zinc (~65), and copper (~64). This question tests knowledge of relative atomic masses in the periodic table, with chromium being the lightest among the options.

Mercury is the only metal that exists as a liquid at standard temperature and pressure (room temperature). It has a melting point of -38.83°C and a boiling point of 356.73°C. This unique property is due to mercury's weak metallic bonding from its filled 4f subshell and relativistic effects that stabilize the 6s electrons. All other metals listed are solids at room temperature.

Bronze is an alloy consisting mainly of copper with tin as the primary additive. The combination of copper and tin creates a harder material than pure copper, which has been used for thousands of years in tools, weapons, and sculptures.

Heavy Spar is the historical name for Barium Sulphate (BaSO4), a white crystalline substance. It gets its name from its high density and was used in various industrial applications.

Mercury has an unusually low melting point of approximately -39°C for a metal, which keeps it liquid at standard room temperature (20-25°C). This property results from its unique electron configuration and weak metallic bonding compared to other metals.

Solder is an alloy primarily composed of tin and lead, used to join metal parts together. The other options listed are either pure metals (gold, silver) or different alloys (steel is iron-carbon).

Ruby and sapphire are both varieties of the mineral corundum, which is crystalline aluminum oxide (Al2O3). The red color of ruby comes from trace chromium impurities, while sapphire's blue color is caused by iron and titanium impurities. Though they appear different, both share the same chemical composition.

Solder is primarily an alloy of lead and tin. The most common solder alloy is 60% tin and 40% lead (60/40 solder) or 63% tin and 37% lead (63/37 solder). This combination has a low melting point, good wetting properties, and strong electrical conductivity, making it ideal for joining electrical components and metal work.

Cu is a metallic solid.

A dry cell uses a carbon rod (graphite) as the positive terminal (cathode). The zinc casing serves as the negative terminal (anode). The carbon rod remains stable during discharge.