Test: Chemistry - 2 - UPSC MCQ

As a gemstone used in jewellery, silicon carbide is called "synthetic moissanite" or just "moissanite". Moissanite is similar to diamond in several important respects it is transparent and hard . Moissanite has become popular as a diamond substitute, and may be misidentified as diamond, since its thermal conductivity is close to that of diamond, more than any other diamond substitute. The properties of carbon fibres, such as high stiffness, high tensile strength, low weight, high chemical resistance, high temperature tolerance and low thermal expansion, make them very popular in aerospace, civil engineering, military, and motor sports. Dichlorodifluoromethane (R-12) is a colourless gas, and usually sold under the brand nameFreon-12, is a chlorofluorocarbon halo-methane (CFC), used as a refrigerant and aerosol spray propellant. In photosynthesis, solar energy is converted to chemical energy. The chemical energy is stored in the form of glucose (sugar). Carbon dioxide, water, and sunlight are used to produce glucose, oxygen, and water.

Sour milk – Lactic acid Vinegar and pickel – Acetic acid Soda water – Carbonic acid Apple – Malic acid

Enriched uranium is a type of uranium in which the percent composition of uranium-235 has been increased through the process of isotope separation. Enriched uranium is a critical component for both civil nuclear power generation and military nuclear weapons. The International Atomic Energy Agency attempts to monitor and control enriched uranium supplies and processes in its efforts to ensure nuclear power generation safety and curb nuclear weapons proliferation.

The energy released from the collapse of the gas into a star causes the centre of the star to become extremely hot. When the core is hot enough, nuclear fusion commences. Fusion is the process where two hydrogen atoms combine to form a helium atom, releasing energy. The fusion reaction is a very efficient process, releasing a huge amount of energy. This is because a single helium atom contains less mass than two hydrogen atoms. The excess mass is released as energy.

Because the humidity inside the fridge is low and extra moisture is absorbed.

Correct option is B. They have very high wavelength

In cold countries, when the temperature of fresh water reaches 4°C, the layers of water near the top in contact with cold air continue to lose heat energy and their temperature falls below 4°C. On cooling below 4°C, these layers do not sink but may rise up as fresh water has a maximum density at 4°C. Due to this, the layer of water at 4°C remains at the bottom and above this layers of water 3°C, 2°C, 1°C and 0°C are formed. Because ice is a poor conductor of heat, it does not absorb heat energy from the water beneath the layer of ice which prevents the water freezing. Thus, aquatic creatures survive in such places.

Nuclear fusion is a nuclear reaction in which two or more atomic nuclei collide at a very high speed and join to form a new type of atomic nucleus.

Two recent studies have examined LPG-fueloil fuel mixes and found that smoke emissions and fuel consumption are reduced but hydrocarbon emissions are increased.

Bio gas is primarily methane (CH₄) and carbon dioxide (CO₂) and may have small amounts of hydrogen sulphide (H₂S), moisture and siloxanes.

Potassium bromide is a salt used to make photographic papers and plates and for process engraving. Gunpowder, also known since the late 19th century as black powder, is a mixture of sulphur, charcoal, and potassium nitrate (saltpeter)—with the sulphur and charcoal acting as fuels, while the saltpeter works as an oxidizer. The principal use of potassium sulphate is as a fertilizer. K₂SO₄ does not contain chloride, which can be harmful to some crops. Potassium sulphate is preferred for these crops, which include tobacco and some fruits and vegetables. A white, acid, crystalline solid or powder, KHC₄H₄O₆, used in baking powder, in the tinning of metals, and as a component of laxatives. Also called cream of tartar.

Nickel silver, also known as German silver, is a copper alloy with nickel and often zinc. Solders are typically made from tin or lead or a combination of both in the ratio of 63:37 respectively. Calcium hypochlorite, also known as bleaching powder, is a chemical compound with formula Ca(ClO)₂. It is widely used for water treatment and as a bleaching agent. This chemical is considered to be relatively stable and has greater available chlorine than sodium hypochlorite (liquid bleach). Hypo solution is the abbreviation for sodium thiosulphate or sodium hyposulphite, a chemical used to fix the image on photographic film after it has been developed.

When CO is not ventilated it binds to haemoglobin, which is the principal oxygencarrying compound in blood; this produces a compound known as carboxyhaemoglobin. The traditional belief is that carbon monoxide toxicity arises from the formation of carboxyhaemoglobin, which decreases the oxygen-carrying capacity of the blood and inhibits the transport, delivery, and utilization of oxygen by the body.

Hard water is not suitable for washing clothes with soap and use in boilers.

Cooking gas consists of mostly liquified butane and isobutane.

CNG – Butane, ethane Coal gas – Hydrogen, methane, CO LPG – Butane, propane Water gas – CO, hydrogen

It inactivates/kills the harmful microorganisms in water.

Carbon, hydrogen and nitrogen were primarily responsible for the origin of life on the earth.

Acid rain is caused by emissions of sulphur dioxide and nitrogen oxide, which react with the water molecules in the atmosphere to produce acids.

It is tested by ammonical silver nitrate solution.