Chemistry Quiz 2

Radioactive elements are made up of atoms whose nuclei are unstable and give off atomic radiation as part of a process of attaining stability. Uranium, Radium, Polonium, Thorium, etc are common radioactive elements. Zirconium is non-radioactive element.

Smoke is formed due to solid dispersed in gas. Smoke is a collection of tiny unburnt particles. It is a collection of tiny solid, liquid and gas particles — mostly carbon (soot), tar, oils and ash. Here solid acts as a dispersed phase and gas acts as a dispersed medium.

High octane fuel contains high content of lead. If tetraethyl lead, Pb(CH₂CH₃)₄, was put into petrol, particles of lead and lead oxide PbO are formed on combustion. This helps the petrol to burn more slowly and smoothly, preventing knocking and giving higher Octane ratings.

Sodium is used in the yellow lamps used for street lighting. Sodium-vapour lamps are good for night-time illumination because of their high efficiency and because the light they produce penetrates mist and fog particularly well.

When a helium atom loses an electron it becomes a positive helium ion. When an atom gains/loses an electron, the atom becomes charged, and is called an ion. If a neutral atom gains an electron, it becomes negative. This kind of ion is called an anion. If a neutral atom loses an electron, it becomes positive. This kind of ion is called a cation.

Ester has a fruity smell due to its volatile nature caused by its chemical composition and conformations. The aroma of an ester is produced when alcohol combines with a carboxylic group (carbon bonded with oxygen atoms). Esters smell partly because they exhibit weak intermolecular forces.

Fructose is the sweetest sugar. Sucrose is second sweetest followed by glucose and lactose.

The mercury and sodium street lamps light up because of atomic emission. An electric discharge takes place when electricity is passed through sodium vapors at low or high pressure. As a result, the valence electron present in sodium atoms becomes excited and emits light. The mercury vapor lamp works by creating an electric current to mercury vapor within a sealed glass jacket.

Rusting of iron takes place due to an oxidation reaction. The iron reacts with water and oxygen to form hydrated iron(III) oxide, which we see as rust. Iron and steel rust when they come into contact with water and oxygen – both are needed for rusting to occur.

Paraffin wax is a colourless soft, solid wax obtained from petroleum, coal or oil shale. It consists of a mixture of hydrocarbon molecules containing between twenty and forty carbon atoms. It's often used in skin-softening salon and spa treatments on the hands, cuticles, and feet.