Rust is composed of iron oxides. In colloquial usage, the term is applied to red oxides, formed by the reaction of iron and oxygen in the presence of water or air moisture. When impure (cast) iron is in contact with water, oxygen, or other strong oxidants, or acids, it rusts. If salt is present, for example in seawater or salt spray, the iron tends to rust more quickly, as a result of electrochemical reactions.

Correct Option: D

Rust is composed of iron oxides. In colloquial usage, the term is applied to red oxides, formed by the reaction of iron and oxygen in the presence of water or air moisture. When impure (cast) iron is in contact with water, oxygen, or other strong oxidants, or acids, it rusts. If salt is present, for example in seawater or salt spray, the iron tends to rust more quickly, as a result of electrochemical reactions.

Brass is an alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties. By comparison, bronze is principally an alloy of copper and tin.

Correct Option: C

Brass is an alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties. By comparison, bronze is principally an alloy of copper and tin.

Water gas, a mixture of carbon monoxide and hydrogen, is produced by treating carbon (in the form of coke or coal) with steam at high temperatures.

Correct Option: C

Water gas, a mixture of carbon monoxide and hydrogen, is produced by treating carbon (in the form of coke or coal) with steam at high temperatures.

Bunker Gear or "Turnout Gear" are terms used by many firefighters to refer to their system of outer protective clothing. Fire fighter used to be made of asbestos in the past. Because of its carcinogenic properties and other harmful effects, it has slowly been replaced by other substitutes. Fire-fighting and working clothes and accessories for firemen, rescuers and industrials made of materials FR cotton, Nomex, Modacryl, FR viscose and others.

Correct Option: B

Bunker Gear or "Turnout Gear" are terms used by many firefighters to refer to their system of outer protective clothing. Fire fighter used to be made of asbestos in the past. Because of its carcinogenic properties and other harmful effects, it has slowly been replaced by other substitutes. Fire-fighting and working clothes and accessories for firemen, rescuers and industrials made of materials FR cotton, Nomex, Modacryl, FR viscose and others.

Calcium carbonate, or CaCO3, is found in natural forms as chalk, limestone, and marble, produced by the sedimentation of the shells of small fossilized snails, shellfish, and coral over millions of years. Calcium hydroxide, traditionally called slaked lime, is an inorganic compound which is obtained when calcium oxide is mixed, or "slaked" with water.

Correct Option: D

Calcium carbonate, or CaCO3, is found in natural forms as chalk, limestone, and marble, produced by the sedimentation of the shells of small fossilized snails, shellfish, and coral over millions of years. Calcium hydroxide, traditionally called slaked lime, is an inorganic compound which is obtained when calcium oxide is mixed, or "slaked" with water.