Dmitri Ivanovich Mendeleev was a Russian chemist and inventor. He formulated the Periodic Law, created his own version of the periodic table of elements, and used it to correct the properties of some already discovered elements and also to predict the properties of eight elements yet to be discovered.
Section-1: General Science - Chemistry Question - 2
The most important form of elemental phosphorus from the perspective of applications and the chemical literature is white phosphorus. It consists of tetrahedral $P_4$ molecules, in which each atom is bound to the other three atoms by a single bond.
This $P_4$ tetrahedron is also present in liquid and gaseous phosphorus up to the temperature of 800 °C (1,470 °F) when it starts decomposing to $P_2$ molecules
Section-1: General Science - Chemistry Question - 3
The formula $ C_6H_5-CO-CH_3$ represents which of the following compounds?
Acetophenone is the organic compound with the formula $ C_6H_5-CO-CH_3$. It is the simplest aromatic ketone. This colourless, viscous liquid is a precursor to useful resins and fragrances.
Acetophenone can be obtained by a variety of methods. In industry, acetophenone is recovered as a by-product of the oxidation of ethylbenzene, which mainly gives ethylbenzene hydroperoxide for use in the production of propylene oxide.
Section-1: General Science - Chemistry Question - 4
Which of the following metal is extracted from sea water?
Seawater contains large amounts of dissolved ions and the four most concentrated metal ones which are magnesium, calcium, potassium and sodium are being commercially extracted today. However, all the other metal ions exist at much lower concentrations.
Section-1: General Science - Chemistry Question - 5
Which of the following element is not a group 18 element of the periodic table?