General Science Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination
[A] To decrease its pH slightly
[B] To increase its pH slightly
[C] To kill the bacteria in Fresh Milk
[D] To turn its color from slight pale to white
The pH of fresh milk is 6, to set it as curd needs the pH below 6. In order to avoid this, the milkman shifts the pH of fresh milk from 6 to slightly alkaline by adding baking soda. Since, the milk is slightly basic than usual milk, acids produced to set the curd are neutralized by the base added. Therefore, it takes longer time for the curd to set.
- Sodium hydroxide
Select the correct option from the codes given below:
[A] Only 1 & 2
[B] Only 1 & 3
[C] Only 2 & 3
[D] 1, 2 & 3
The process is known as chlor-alkali process. It is names so because the products formed chlor- for chlorine and alkali for sodium hydroxide. In this process, chlorine is given off at anode, hydrogen gas at the cathode and sodium hydroxide solution is formed near the cathode. The three products formed in this process are all useful.
[C] Carbon Dioxide
[D] Carbon Monoxide
When excess amount of carbon dioxide gas is passed through lime water, it turns lime water milky due to the formation of Calcium Carbonate (CaCO3).
[A] Washing Soda
[B] Baking Soda
[C] Soda Lime
[D] Caustic Soda
Sodium bicarbonate (Baking Soda) is one of the main components of the common “black snake” firework. The effect is caused by the thermal decomposition, which produces carbon dioxide gas to produce a long snake-like ash as a combustion product of the other main component, sucrose.
[A] Hydrochloric Acid
[B] Sulphuric Acid
[C] Nitric Acid
[D] Phosphoric Acid
Dilute sulfuric acid (H2SO4) serves as the electrolyte in a lead storage battery. The electrodes of the cells in a lead storage battery consist of lead grids. The openings of the anodic grid is filled with spongy (porous) lead. The openings of the cathodic grid is filled with lead dioxide (PBO2).
[B] Cast Iron
[C] Pig Iron
[D] Wrought Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element (by mass) forming the planet Earth as a whole, forming much of Earth’s outer and inner core. It is the fourth most common element in the Earth’s crust. Wrought iron is the purest form of iron. It contains less than 0.25% carbon. Wrought iron, one of the two forms in which iron is obtained by smelting; the other is cast iron. Wrought iron is a soft, ductile, fibrous variety that is produced from a semi fused mass of relatively pure iron globules partially surrounded by slag. It usually contains less than 0.1 per cent carbon and 1 or 2 per cent slag. It is superior for most purposes to cast iron, which is overly hard and brittle owing to its high carbon content.
An amalgam is a substance formed by the reaction of mercury with another metal. Almost all metals can form amalgams with mercury, a notable exception being iron. Silver-mercury amalgams are important in dentistry, and gold-mercury amalgam is used in the extraction of gold from ore. Dentistry has used alloys of mercury with metals such as silver, copper, indium, tin and zinc. Amalgam is an “excellent and versatile restorative material” and is used in dentistry for a number of reasons.
Nuclear fission is either a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts (lighter nuclei), often producing free neutrons and photons (in the form of gamma rays), and releasing a very large amount of energy, even by the energetic standards of radioactive decay. Fission, as encountered in the modern world, is usually a deliberately produced man-made nuclear reaction induced by a neutron. In nuclear fission, a large nucleus is split into two medium-sized nuclei. Only a few nuclei are known to undergo fission. Nuclear power plants currently in use depend primarily on the fission of uranium-235 and plutonium-239. When a nucleus of uranium-235 undergoes fission, it splits into two smaller atoms and, at the same time, releases neutrons ( n) and energy. Some of these neutrons are absorbed by other atoms of uranium-235. In turn, these atoms split apart, releasing more energy and more neutrons. In nuclear power plants, the energy released by the controlled fission of uranium-235 is collected in the reactor and used to produce steam in a heat exchanger. The steam then drives a turbine to produce electricity. Energy generation can be regulated by inserting control rods between the fuel rods in the reactor to absorb excess neutrons, thereby controlling the rate of the chain reaction. A typical nuclear power plant in operation today uses about 2 kg uranium-235 to generate 1000 megawatts of electricity. About 5600 tons (5.1 X 106 kg) of coal is required to produce the same amount of electricity in a conventional power plant.Uranium-235 (natural abundance 0.71%) is very scarce and difficult to separate from uranium-238 (natural abundance 99.28%). The much more abundant uranium-238 does not undergo fission and therefore cannot be used as a fuel for nuclear reactors. However, if uranium-238 is bombarded with neutrons (from uranium-235, for example), it absorbs a neutron and is transformed into uranium-239. This isotope undergoes beta emission to generate neptunium-239, which, in turn, undergoes another beta emission to produce plutonium-239. Plutonium-239 also undergoes fission, with the production of more energy and more neutrons. These neutrons can then be used to breed more plutonium-239 from uranium-238. Thus, a so-called breeder reactor can produce its own supply of fissionable material. Several breeder reactors are now functioning in Europe.
[B] Carbon dioxide
[C] Carbon Monoxide
[D] Chloro fluorocarbons
A greenhouse gas (sometimes abbreviated GHG) is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. The primary greenhouse gases in the Earth’s atmosphere are water vapour, carbon dioxide, methane, nitrous oxide, and ozone. Nitrous oxide (N2O) gas should not be confused with nitric oxide (NO) or nitrogen dioxide (NO2). Neither nitric oxide nor nitrogen dioxide is greenhouse gases, although they are important in the process of creation of tropospheric ozone which is a greenhouse gas. There are several sources of nitrous oxide, both natural and anthropogenic (human), to the atmosphere with many of these sources difficult to measure. Because of this, there is general agreement that the atmospheric sources and sinks of nitrous oxide are difficult to bring into balance.
Which among the following is a crystalline form of Quartz?
Silica is synonymous with silicon dioxide (SiO2). Silicon and oxygen are the two most abundant elements in the earth’s crust. Silica is commonly found in nature as sand. Silica exists in many different forms that can be crystalline as well as non-crystalline (amorphous). Quartz is the most common form of crystalline silica and is the second most common mineral on the earth’s surface. It is found in almost every type of rock i.e. igneous, metamorphic and sedimentary. Since it is so abundant, quartz is present in nearly all mining operations. Silica, or silicon dioxide (SiO2), is a group IV metal oxide, which naturally occurs in both crystalline and amorphous forms. The various forms of crystalline silica are α-quartz, β-quartz, α-tridymite, β-tridymite, α-cristobalite, β-cristobalite, keatite, coesite, stishovite, and moganite. The most abundant form of silica is α-quartz, and the term quartz is often used in place of the general term crystalline silica.