he first human-made plastic was made by Alexander Parkes in 1855, when he synthesized celluloid. The new discovery found its use in photographic films, but it could not be used for making containers or insulators for electric circuits.

The first true plastic was made in 1909 by Leo Baekeland, who synthesized Bakelite. The hard plastic could be used to make handles, auto parts, etc. The First World War witnessed improvements in the manufacture of polystyrene and polyvinyl chloride, which found use in plumbing equipment and electric wire insulation. Nylon was synthesized in the 1930s. By 1950, plastics became quite popular and as a result we can see them everywhere today

Please note that the Cycloalkanes with more than 20 carbon atoms are called Cycloparaffins. The cycloalkanes have the same properties as the alkanes but they have `Higher Boiling & Melting points`. This is because of the stronger dispersion forces between the atoms known as London Forces.

Pure diamond should transmit visible light and appear as a clear colorless crystal. Colors in diamond originate from lattice defects and impurities. The diamond crystal lattice is exceptionally strong and only atoms of nitrogen, boron and hydrogen can be introduced into diamond during the growth at significant concentrations (up to atomic percents). Nitrogen gives yellowish color while the Boron gives bluish color.

Above 70 °C, sodium bicarbonate gradually decomposes into sodium carbonate, water and carbon dioxide as follows –

2 NaHCO3 → Na2CO3 + H2O + CO2 ,

In bakery, it reacts with other components or decomposes at higher temperature to release carbon dioxide, which causes dough to rise.

White Gold has no silver at all. It has nickel, manganese or palladium usually

Methyl Alcohol or methanol is frequently used as a denaturant additive for ethanol manufactured for industrial uses.

Carbamide is another name of Urea, an organic compound with chemical formula CO(NH₂)₂. This name indicates that Urea is an amide in which two –NH₂ groups are joined by a carbonyl (C=O) functional group.

The auto-ignition temperature of a liquid, gas or vapor is the temperature at which the substance will ignite without any external heat source. Here is the temperature of some gases: 
Methane -580 °C 
Hydrogen -560 °C 
Propane -493 °C 
Ethylene -425 °C 
Acetylene -305 °C 
Naphtha -290 °C 
Carbon disulfide -102 °C

fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At)

selenium is a chalcogen