Chemistry (Part-2) (CDS-Solved Paper)

For degumming of the raw material in paper manufacturing industries bleaching powder is used. The two main raw materials required for the manufacture of bleaching powder are high grade lime and chlorine.

Bleaching powder, also known as chlorinated lime, is a yellowish white powder easily soluble in water. The major use of bleaching powder is in paper industry, textile industry and oil industry. It is also used in all chemical industry where bleaching is required.

Dolomite is used in agriculture to raise the pH of overly acidic soil and provide nutrients for plants. Dolomite is an example of an agricultural lime, or crushed stone, applied to the soil with beneficial properties for healthy plant growth.

Dolomite contains calcium carbonate and magnesium carbonate, two basic pH raising ingredients that counter act the acids in soil and peat. It gradually dissolves into the soil, neutralising acidity from further watering and fertilising.

Dolomite also helps plants absorb nutrients more effectively. However, dolomite can harm plants if used in the wrong soil type or if used in excess. Mineral content testing and pH testing are both recommended before choosing dolomite over other agricultural limes.

Lithium hydrogen carbonate does not exist in solid form because lithium hydrogen carbonate (LiHCO₃) is found in solution form. Lithium is a chemical element with the symbol Li and atomic number 3. It is a soft, silver-white metal belonging to the alkali metal group of chemical elements.

Ferromagnetism is the basic mechanism by which certain materials, such as iron are attracted to magnets. Only a few substances are ferromagnetic. The common ones are iron, nickel, cobalt and most of their alloys, some compounds of rare earth metals, and a few naturally occurring minerals, such as lodestone. Thus, liquids and gases never show the ferromagnetic property.

In gamma decay, a nucleus changes from a higher energy state to a lower energy state through the emission of electromagnetic radiation. The number of protons and neutrons in the nucleus remain unchanged in this process, so the parent and atoms are the same chemical elements.

Atmospheric pressure is also called barometric pressure. It is the pressure exerted by the weight of air in the atmosphere of the Earth. In most circumstances, atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point.
Low pressure area have less atmospheric mass above their location. High pressure area have more atmospheric mass above their location.

Hydrogen has two possible oxidation numbers +1and −1. It has an oxidation number +1, when it is bonded to non-metals. For the compound hydrochloric acid, hydrogen is bonded to chlorine, a non-metal, so the oxidation number of hydrogen is +1. Hydrogen has an oxidation number of −1, when it is bonded to a metal. For the compound sodium hydride, hydrogen is bonded to sodium, which is a metal, so the oxidation number is –1.

The standard hydrogen electrode is a redox electrode, which forms the basis of the thermodynamic scale of oxidation-reduction potentials. Its absolute electrode potential is estimated to be 4.44 V at 25°C.
To form a basis for comparison with all other electrode reactions, hydrogen standard electrode potential (E°) is declared to be zero volts at all temperature. The concentration of both reduced and oxidised form is maintained at unity. It implies that the pressure of hydrogen gas is 1 bar and the activity of hydrogen ions in the solution is unity.

People sprinkle water on the roof because when this water gets evaporated they take up some of the heat from the roof for the process of evaporation. As some of the heat gets released, the roof becomes cooler making the rooms also cool.

Bakelite is a type of plastic (i.e. polythene) once moulded, does not melt in the presence of heat. It is used for making electrical appliances, handles of crockery, etc.