Chemistry

Jabir bin Hayan is widely regarded as the founder of chemistry due to his pioneering work in alchemy and the development of experimental techniques that laid the foundation for modern chemistry.

Fluorine is the most electronegative element in the periodic table due to its high effective nuclear charge and small atomic radius, which strongly attracts electrons in a chemical bond.

Diamond is an allotrope of carbon, meaning it is composed entirely of carbon atoms arranged in a crystal lattice. Therefore, the correct answer is Carbon.

The chemical name of table salt is Sodium Chloride, which is represented by the formula NaCl. This is the common salt used in cooking and food seasoning.

Sea water contains dissolved salts which lower its freezing point compared to fresh water sources like river or canal water. Therefore, sea water will freeze last among the options given.

Salinity of seawater is typically expressed as the amount of common salt (sodium chloride) per 1 kilogram of seawater, making option A correct.

Oxygen was discovered in 1774 by Joseph Priestley, who isolated it by heating mercuric oxide. This discovery is well-documented in the history of chemistry.

Distillation is the process used to separate components of a solution based on differences in boiling points. In the case of a common salt (sodium chloride) solution, water can be evaporated and then condensed to recover pure water, while salt remains as residue, thus both salt and water are recovered.

The drum of a photostat (photocopier) machine is typically coated with selenium because of its photoconductive properties, which allow it to hold an electrostatic charge when exposed to light, essential for the copying process.

Zirconium is essential in nuclear reactors because it has a low neutron absorption cross-section and excellent corrosion resistance, making it ideal for cladding fuel rods. The other elements listed are not commonly used for this purpose.