Chemistry GK Questions Quiz-14

Chemistry GK Questions Quiz-14

Chemistry Multiple Choice Questions (MCQs) Quiz for State and UPSC Civil Services Examinations. Objective Questions on Chemistry for competitive examinations.

    261. Which of the following metals causes Itai-Itai disease ?

    (1) Cadmium 
    (2) Chromium
    (3) Cobalt 
    (4) Copper
    Answer:
    261. (1) Itai-itai disease was the documented case of mass cadmium poisoning in Toyama Prefecture, Japan, starting around 1912. The cadmium poisoning caused softening of the bones and kidney failure. The disease is named for the severe pains caused in the joints and spine. The cadmium was released into rivers by mining companies in the mountains. The mining companies were successfully sued for the damage. Itai-itai disease is known as one of the Four Big Pollution Diseases of Japan. Itai-itai disease was caused by cadmium poisoning due to mining in Toyama Prefecture. The cadmium and other heavy metals accumulated at the bottom of the river and in the water of the river. This water was then used to irrigate the rice fields. The rice absorbed heavy metals, especially the cadmium. The cadmium accumulated in the people eating contaminated rice.

    262. Glycol is added to aviation gasoline because it

    (1) reduces evaporation of petrol
    (2) increases efficiency of petrol
    (3) prevents freezing of petrol
    (4) reduces consumption of petrol
    Answer:
    262. (3) Ethylene glycol (IUPAC name: ethane-1,2-diol) is an organic compound widely used as an automotive antifreeze and a precursor to polymers. In its pure form, it is an odorless, colourless, syrupy, sweettasting liquid. Ethylene glycol is toxic, and ingestion can result in death. Due to its low freezing point ethylene glycol resists freezing. A mixture of 60% ethylene glycol and 40% water freezes at -45 degree C (-49 degree F). Diethylene glycol behaves similarly. It is used as a deicing fluid for windshields and aircraft. The antifreeze capabilities of ethylene glycol have made it an important component of vitrification (anticrystallization) mixtures for low-temperature preservation of biological tissues and organs.

    263. Which one of the following minerals is found in Monazite sand ?

    (1) Potassium 
    (2) Uranium
    (3) Thorium 
    (4) Sodium
    Answer:
    263. (3) Monazite is a reddish-brown phosphate mineral containing rare earth metals. It occurs usually in small isolated crystals. There are actually at least four different kinds of monazite, depending on relative elemental composition of the mineral. Monazite is an important ore for thorium, lanthanum, and cerium. It is often found in placer deposits. The deposits in India are particularly rich in monazite. It has a hardness of 5.0 to 5.5 and is relatively dense, about 4.6 to 5.7 g/ cm3. Because of the presence of thorium within monazite, it can be radioactive. If samples are kept, they should be placed away from minerals that can be damaged by radiation. Because of its radioactive nature, the monazite within rocks is a useful tool for dating geological events, such as heating or deformation of the rock.

    264. Now-a-days yellow lamps are frequently used as street lights. Which of the following gases is used in these lamps ?

    (1) Sodium 
    (2) Neon
    (3) Hydrogen 
    (4) Nitrogen
    Answer:
    264. (1) A sodium-vapor lamp is a gas-discharge lamp that uses sodium in an excited state to produce light. There are two varieties of such lamps: low pressure and high pressure. Low-pressure sodium lamps are the most efficient electrical light sources, but their yellow light restricts applications to outdoor lighting such as street lamps. High-pressure sodium lamps have a broader spectrum of light but poorer colour rendering than other types. Because sodium vapor lamps cause less light pollution than mercury-vapor lamps, many cities that have large astronomical observatories employ them.

    265. The element which is used for vulcanizing rubber

    (1) Sulphur 
    (2) Bromine
    (3) Silicon 
    (4) Phosphorus
    Answer:
    265. (1) Vulcanization is a chemical process for converting rubber or related polymers into more durable materials via the addition of sulfur or other equivalent “curatives” or “accelerators”. By far the most common vulcanizing methods depend on sulfur.

    266. Which of the following is responsible for the extra strength of pyrex glass ?

    (1) Potassium Carbonate
    (2) Lead Oxide
    (3) Borax
    (4) Ferric Oxide
    Answer:
    266. (3) Older clear-glass Pyrex manufactured by Corning before 1998, Arc International’s Pyrex products, and Pyrex laboratory glassware is made of borosilicate glass. According to the National Institute of Standards and Technology, borosilicate Pyrex is composed of (as percentage of weight): 14% boron, 51% oxygen, 0.3% sodium, 1% aluminium, 38% silicon, and less than 1% potassium. Pyrex glass cookware manufactured by World Kitchen is made of tempered soda-lime glass instead of borosilicate. World Kitchen justified this change by stating that soda-lime glass was cheaper to produce, is the most common form of glass used in bakeware in the US, and that it also had higher mechanical strength than borosilicate— making it more resistant to breakage when dropped, which it believed to be the most common cause of breakage in glass bakeware.

    267. Which of the following could be used as fuel in propellant or rockets ?

    (1) Liquid Hydrogen + Liquid Nitrogen
    (2) Liquid Oxygen + Liquid Argon
    (3) Liquid Nitrogen + Liquid Oxygen
    (4) Liquid Hydrogen + Liquid Oxygen
    Answer:
    267. (4) LOX and liquid hydrogen, used in the Space Shuttle orbiter, the Centaur upper stage of the Atlas V, Saturn V upper stages, the newer Delta IV rocket, the H-IIA rocket, and most stages of the European Ariane rockets. Liquid fueled rockets have higher specific impulse than solid rockets and are capable of being throttled, shut down, and restarted. Only the combustion chamber of a liquid fueled rocket needs to withstand high combustion pressures and temperatures and they can be regeneratively cooled by the liquid propellant. For these reasons, most orbital launch vehicles use liquid propellants.The primary performance advantage of liquid propellants is due to the oxidizer. Several practical liquid oxidizers (liquid oxygen, nitrogen tetroxide, and hydrogen peroxide) are available which have better specific impulse than the ammonium perchlorate used in most solid rockets, when paired with comparable fuels.

    268. The addition of gypsum to portland cement helps in :

    (1) increasing the strength of cement
    (2) rapid setting of cement
    (3) preventing rapid setting of cement
    (4) reduction in the cost of cement
    Answer:
    268. (3) Portland cement clinker is a hydraulic material which shall consist of at least two-thirds by mass of calcium silicates, the remainder consisting of aluminium- and iron-containing clinker phases and other compounds. The ratio of CaO to SiO2 shall not be less than 2.0. The magnesium oxide content (MgO) shall not exceed 5.0% by mass. Cement sets when mixed with water by way of a complex series of chemical reactions still only partly understood. The different constituents slowly crystallise and the interlocking of their crystals gives cement its strength. Carbon dioxide is slowly absorbed to convert the portlandite (Ca(OH)2) into insoluble calcium carbonate. After the initial setting, immersion in warm water will speed up setting. Gypsum is added as an inhibitor to prevent flash setting.

    269. The constituents of automobile exhaust that can cause cancer is/are :

    (1) Oxides of nitrogen
    (2) Carbon monoxide
    (3) Polycyclic hydrocarbons
    (4) Lead
    Answer:
    269. (4) Lead is a naturally occurring bluish-gray metal found in small amounts in the earth’s crust. In the past, when lead was added to gasoline, breathing automobile exhaust was the major source of lead
    exposure for most people. Lead in the exhaust also contaminated the soil near roads. Another major
    source of exposure is old paint that contains lead. Lead has been found to be carcinogen. A substance
    that causes cancer or helps cancer grow is called a carcinogen. Several studies have looked for a link
    between exposure to lead in the workplace (mainly among battery workers and smelter workers) and lung cancer. Some of these studies have found a small increase in lung cancer risk. Studies have also looked at possible links between workplace exposures to lead and other cancers, including cancers of the brain, kidney, bladder, colon, and rectum.

    270. Hard steel contains

    (1) 2 to 5 per cent carbon
    (2) 0.5 to 1.5 per cent carbon
    (3) 0.1 to 0.4 per cent carbon
    (4) 0.01 to 0.04 per cent carbon
    Answer:
    270. (2) The term hardened steel is often used for a medium or high carbon steel that has been given the heat treatments of quenching followed by tempering. The quenching results in the formation of metastable martensite, the fraction of which is reduced to the desired amount during tempering. This is the most common state for finished articles such as tools and machine parts. In contrast, the same steel
    composition in annealed state will be softer as required for forming and machining. Carbon steels which can successfully undergo heat-treatment have carbon content in the range of 0.30–1.70% by weight. Trace impurities of various other elements can have a significant effect on the quality of the resulting steel. Trace amounts of sulfur in particular make the steel red-short.

    271. Cement is formed by strongly heating a mixture of

    (1) limestone and graphite
    (2) limestone and clay
    (3) chalk and graphite
    (4) clay and graphite
    Answer:
    271. (2) Cement is made by heating limestone (calcium carbonate) with small quantities of other materials (such as clay) to 1450 degree C in a kiln, in a process known as calcination, whereby a molecule of carbon dioxide is liberated from the calcium carbonate to form calcium oxide, or quicklime, which is then blended with the other materials that have been included in the mix. The resulting hard substance, called ‘clinker’, is then ground with a small amount of gypsum into a powder to make ‘Ordinary Portland Cement’, the most commonly used type of cement (often referred to as
    OPC). Portland cement is a basic ingredient of concrete, mortar and most non-specialty grout. The
    most common use for Portland cement is in the production of concrete.

    272. Glass is a

    (1) superheated solid
    (2) supercooled liquid
    (3) supercooled gas
    (4) superheated liquid
    Answer:
    272. (2) Glass is an amorphous (non-crystalline) solid material. Glasses are typically brittle and optically transparent. The standard definition of a glass (or vitreous solid) is a solid formed by rapid melt quenching. However, the term glass is often used to describe any amorphous solid that exhibits a glass transition temperature Tg. If the cooling is sufficiently rapid (relative to the characteristic crystallization time) then crystallization is prevented and instead the disordered atomic configuration of the super-cooled liquid is frozen into the solid state at Tg. Generally, the structure of a glass exists in a meta-stable state with respect to its crystalline form.

    273. The temperature of oxy-acetylene flame is around

    (1) 2800°C 
    (2) 3200°C
    (3) 4000°C 
    (4) 1500°C
    Answer:
    273. (2) Flames are formed when a fuel gas, like acetylene, reacts with a support gas such as oxygen. This reaction creates a lot of heat and light, which we see as a flame. An oxygen acetylene flame can create temperatures over 3200°C. Pure oxygen, instead of air (20% oxygen/80% nitrogen), is used to increase the flame temperature to allow localized melting of the work piece material (e.g. steel) in a room environment. A common propane/air flame burns at about 3,630 degree F (2,000 degree C), a propane/ oxygen flame burns at about 4,530 degree F (2,500 degree C), and an acetylene/oxygen flame burns at about 6,330 degree F (3,500 degree C).

    274. The Refrigerant ‘FREON' is

    (1) Calcium Tetra Fluoride
    (2) Difluoro Dichloro Methane
    (3) Fluorspar and Felspar
    (4) Hydrofluosilicic Acid
    Answer:
    274. (2) Dichlorodifluoromethane (R-12), is a colourless gas, and usually sold under the brand name Freon-12, is a chlorofluorocarbon halomethane (CFC), used as a refrigerant and aerosol spray propellant. Complying with the Montreal Protocol, its manufacture was banned in the United States along with many other countries in 1994 due to concerns about damage to the ozone layer. It is soluble in many organic solvents. It can be prepared by reacting carbon tetrachloride with hydrogen fluoride in the presence of a catalytic amount of antimony pentachloride. This reaction can also produce trichlorofluoromethane (CCl3F), chlorotrifluoromethane (CClF3) and tetrafluoromethane (CF4).

    275. A balloon filled with helium rises in air because

    (1) air exerts an upward force on the balloon
    (2) the balloon is weightless
    (3) helium is less dense than air
    (4) helium pushes down on the air below the balloon
    Answer:
    275. (3) A gas balloon is any balloon that stays aloft due to being filled with a gas less dense than air or lighter than air (such as helium or hydrogen). A gas balloon may also be called a Charlière for its inventor, the Frenchman Jacques Charles. Today, familiar gas balloons include large blimps and small rubber party balloons. Blimps have displaced zeppelins (which are not balloons) as the dominant form of airship. Gas balloons remained popular throughout the age before powered flight. They could fly higher and further than hot-air balloons, but were more dangerous as they were usually filled with hydrogen gas (which, unlike helium, could be easily mass-manufactured). Gas balloons were used in the American Civil War by Thaddeus Lowe.

    276. Glass is a –

    (1) pure solid
    (2) supercooled liquid
    (3) gel
    (4) polymer
    Answer:
    276. (2) Glass is an amorphous (non-crystalline) solid material. Glasses are typically brittle and optically transparent. The standard definition of a glass (or vitreous solid) is a solid formed by rapid melt quenching. However, the term glass is often used to describe any amorphous solid that exhibits a glass transition temperature Tg.

    277. Uranium eventually decays into a stable isotope of –

    (1) Radium 
    (2) Thorium
    (3) Lead 
    (4) Polonium
    Answer:
    277. (3) Natural uranium consists of three major isotopes: U238 (99.28% natural abundance), U235 (0.71%), and U234 (0.0054%). All three are radioactive, emitting alpha particles, with the exception that all three of these isotopes have small probabilities of undergoing spontaneous fission, rather than alpha emission. U238 is usually an alpha emitter (occasionally, it undergoes spontaneous fission), decaying through the “Uranium Series” of nuclear decay, which has 18 members, all of which eventually decay into Pb206, by a variety of different decay paths. The decay series of U235, which
    is called the actinium series has 15 members, all of which eventually decay into Pb207. The constant rates of decay in these decay series makes the comparison of the ratios of parent to daughter elements useful in radiometric dating.

    278. Which of the toxic heavy metals is found in modern tannery industries ?

    (1) Nickel 
    (2) Zinc
    (3) Chromium
    (4) Lead
    Answer:
    278. (3) Chromium is mainly found in waste from the chrome tanning process; it occurs as part of the
    retanning system and is displaced from leathers during retanning and dyeing processes. This chrome is
    discharged from processes in soluble form; however, when mixed with tannery waste waters from other
    processes (especially if proteins are present), the reaction is very rapid. Precipitates are formed, mainly
    protein-chrome, which add to sludge generation. If chrome discharges are excessive, the chromium might remain in the solution. Even in low concentrations, it has a toxic effect upon daphnia, thus disrupting the food chain for fish life and possibly inhibiting photosynthesis.

    279. Which of the following contains high content of lead?

    (1) Coal
    (2) Cooking gas
    (3) High octane fuel
    (4) Low octane fuel
    Answer:
    279. (3) A high-octane-rated fuel, such gasoline contains lead. Straight-run gasoline is distilled directly from crude oil. Once the leading source of fuel, its low octane rating required lead additives. Most countries have phased out leaded fuel. Different additives have replaced the lead compounds. The most popular additives include aromatic hydrocarbons, ethers and alcohol (usually ethanol or methanol). Lead used to be added to petrol and this was the source of high levels of lead in the air.

    280. Stainless steel is an alloy of

    (1) chromium and carbon
    (2) chromium, carbon and iron
    (3) chromium and iron
    (4) carbon and iron
    Answer:
    280. (2) Steel is an alloy made by combining iron and other elements, the most common of these being carbon. When carbon is used, its content in the steel is between 0.2% and 2.1% by weight, depending on the grade. Other alloying elements sometimes used are manganese, chromium, vanadium and tungsten. Stainless steel s defined as a steel alloy with a minimum of 10.5% to 11% chromium content by mass. Stainless steel differs from carbon steel by the amount of chromium present. Unprotected carbon steel rusts readily when exposed to air and moisture. Stainless steels contain sufficient chromium to form a passive film of chromium oxide, which prevents further surface corrosion and blocks corrosion from spreading into the metal’s internal structure, and due to the similar size of the steel and oxide molecules they bond very strongly and remain attached to the surface.


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