Q.1 Which among the following are the biopesticides ? 1) Bacteria 2) Virus 3) Fungi 4) Proteins Codes: A) 1 & 3 B) 1,3,4 C) 1,2,3 D) 1,2,3,4 Ans. D • In the EU, biopesticides have been defined as "a form of pesticide based on micro-organisms or natural products". • the US EPA states that they "include naturally occurring substances that control pests (biochemical pesticides), microorganisms that control pests (microbial pesticides), and pesticidal substances produced by plants containing added genetic material (plant-incorporated protectants) or PIPs". Q.2 Which among the following methods are used for the water disinfection ? 1) Ozonation 2) Chloramine 3) UV radiation 4) Chlorination Codes: A) 1,3,4 B) 2,3,4 C) 1,2,3 D) 1,2,3,4 Ans. D Q.3 Which among the following regarding Chlorination are correct ? 1) It is a process used in other water sources to reduce the bacterial and algal residue in the water 2) Chlorine is highly disinfectant which kills the pathogens through the oxidation of the organic molecules 3) It acts by disintegrating the cell wall of the microorganisms Codes: A) 1 & 3 B) 2 & 3 C) 1 & 2 D) 1,2,3 Ans. D Water chlorination is the process of adding chlorine (Cl2) or hypochlorite to water as a method of water purification to make it fit for human consumption as drinking water. In particular, chlorination is used to prevent the spread of waterborne diseases. Q.4 Which among the following statements regarding water purification technique are correct ? 1) In Situ Chemical Oxidation is the remediation technique used for soil and groundwater remediation to reduce the concentrations of environmental contaminants 2) UV radiation & ozone treatment leaves no residual disinfectant in the water Codes: A) Only 1 B) Only 2 C) Both are correct D) Both are incorrect Ans. C Additional treatment options 1. Water fluoridation: in many areas fluoride is added to water with the goal of preventing tooth decay. Fluoride is usually added after the disinfection process. In the U.S., fluoridation is usually accomplished by the addition of hexafluorosilicic acid, which decomposes in water, yielding fluoride ions. 2. Water conditioning: This is a method of reducing the effects of hard water. In water systems subject to heating hardness salts can be deposited as the decomposition of bicarbonate ions creates carbonate ions that precipitate out of solution. Water with high concentrations of hardness salts can be treated with soda ash (sodium carbonate) which precipitates out the excess salts, through the common-ion effect, producing calcium carbonate of very high purity. The precipitated calcium carbonate is traditionally sold to the manufacturers of toothpaste. Several other methods of industrial and residential water treatment are claimed (without general scientific acceptance) to include the use of magnetic and/or electrical fields reducing the effects of hard water. 3. Plumbosolvency reduction: In areas with naturally acidic waters of low conductivity (i.e. surface rainfall in upland mountains of igneous rocks), the water may be capable of dissolving lead from any lead pipes that it is carried in. The addition of small quantities of phosphate ion and increasing the pH slightly both assist in greatly reducing plumbo-solvency by creating insoluble lead salts on the inner surfaces of the pipes. 4. Radium Removal: Some groundwater sources contain radium, a radioactive chemical element. Typical sources include many groundwater sources north of the Illinois Riverin Illinois. Radium can be removed by ion exchange, or by water conditioning. The back flush or sludge that is produced is, however, a low-level radioactive waste. 5. Fluoride Removal: Although fluoride is added to water in many areas, some areas of the world have excessive levels of natural fluoride in the source water. Excessive levels can be toxic or cause undesirable cosmetic effects such as staining of teeth. Methods of reducing fluoride levels is through treatment with activated alumina and bone charfilter media. Other water purification techniques Other popular methods for purifying water, especially for local private supplies are listed below. In some countries some of these methods are also used for large scale municipal supplies. Particularly important are distillation (de-salination of seawater) and reverse osmosis. 1. Boiling: Bringing it to its boiling point at 100 °C (212 °F), is the oldest and most effective way since it eliminates most microbes causing intestine related diseases, but it cannot remove chemical toxins or impurities. For human health, complete sterilization of water is not required, since the heat resistant microbes are not intestine affecting. The traditional advice of boiling water for ten minutes is mainly for additional safety, since microbes start getting eliminated at temperatures greater than 60 °C (140 °F). Though the boiling point decreases with increasing altitude, it is not enough to affect the disinfecting process. In areas where the water is "hard" (that is, containing significant dissolved calcium salts), boiling decomposes the bicarbonate ions, resulting in partial precipitation as calcium carbonate. This is the "fur" that builds up on kettle elements, etc., in hard water areas. With the exception of calcium, boiling does not remove solutes of higher boiling point than water and in fact increases their concentration (due to some water being lost as vapour). Boiling does not leave a residual disinfectant in the water. Therefore, water that is boiled and then stored for any length of time may acquire new pathogens. 2. Granular Activated Carbon filtering: a form of activated carbon with a high surface area, adsorbs many compounds including many toxic compounds. Water passing through activated carbon is commonly used in municipal regions with organic contamination, taste or odors. Many household water filters and fish tanks use activated carbon filters to further purify the water. Household filters for drinking water sometimes contain silver as metallic silver nanoparticle. If water is held in the carbon block for longer period, microorganisms can grow inside which results in fouling and contamination. Silver nanoparticles are excellent anti-bacterial material and they can decompose toxic halo-organic compounds such as pesticides into non-toxic organic products. 3. Distillation involves boiling the water to produce water vapour. The vapour contacts a cool surface where it condenses as a liquid. Because the solutes are not normally vaporised, they remain in the boiling solution. Even distillation does not completely purify water, because of contaminants with similar boiling points and droplets of unvapourised liquid carried with the steam. However, 99.9% pure water can be obtained by distillation. 4. Reverse osmosis: Mechanical pressure is applied to an impure solution to force pure water through a semi-permeable membrane. Reverse osmosis is theoretically the most thorough method of large scale water purification available, although perfect semi-permeable membranes are difficult to create. Unless membranes are well-maintained,algae and other life forms can colonize the membranes. 5. The use of iron in removing arsenic from water. See Arsenic contamination of groundwater. 6. Direct contact membrane distillation (DCMD). Applicable to desalination. Heated seawater is passed along the surface of a hydrophobic polymer membrane. Evaporated water passes from the hot side through pores in the membrane into a stream of cold pure water on the other side. The difference in vapour pressure between the hot and cold side helps to push water molecules through. 7. Desalination – is a process by which saline water (generally sea water) is converted to fresh water. The most common desalination processes are distillation and reverse osmosis. Desalination is currently expensive compared to most alternative sources of water, and only a very small fraction of total human use is satisfied by desalination. It is only economically practical for high-valued uses (such as household and industrial uses) in arid areas. 8. Gas hydrate crystals centrifuge method. If carbon dioxide or other low molecular weight gas is mixed with contaminated water at high pressure and low temperature, gas hydrate crystals will form exothermically. Separation of the crystalline hydrate may be performed by centrifuge or sedimentation and decanting. Water can be released from the hydrate crystals by heating 9. In Situ Chemical Oxidation, a form of advanced oxidation processes and advanced oxidation technology, is an environmental remediation technique used for soil and/or groundwater remediation to reduce the concentrations of targeted environmental contaminants to acceptable levels. ISCO is accomplished by injecting or otherwise introducing strong chemical oxidizers directly into the contaminated medium (soil or groundwater) to destroy chemical contaminants in place. It can be used to remediate a variety of organic compounds, including some that are resistant to natural degradation. Q.5 Which of the following are the applications of Chlorofluorocarbons ? 1) Blowing agent for foams 2) Refrigeration 3) Cleaning agents 4) Degreasing agents Codes: A) 2 & 3 B) 1 & 2 C) 1,2,3 D) 1,2,3,4 Ans. D A chlorofluorocarbon (CFC) is an organic compound that contains only carbon, chlorine, and fluorine, produced as a volatile derivative of methane, ethane, and propane. They are also commonly known by the DuPont brand name Freon. The most common representative is dichlorodifluoromethane (R-12 or Freon-12). Many CFCs have been widely used as refrigerants, propellants (in aerosol applications), and solvents. The manufacture of such compounds has been phased out under the Montreal Protocol, and are being replaced with products such as HFCs (e.g., R-410A), hydrocarbons, and CO2, because CFCs contribute to ozone depletion in the upper atmosphere. Q.6 Antimatters can be produced through which of the following ? 1) Positrons 2) Anti protons 3) Anti neutrons 4) Anti hydrogen atoms 5) Anti helium atoms Codes: A) 1,3,4,5 B) 2,3,4,5 C) 1,2,3,4 D) 1,2,3,4,5 Ans. D In particle physics, antimatter is material composed of antiparticles, which have the same mass as particles of ordinary matter but have oppositecharge and other particle properties such as lepton and baryon number. Encounters between particles and antiparticles lead to the annihilation of both, giving rise to varying proportions of high-energy photons (gamma rays), neutrinos, and lower-mass particle–antiparticle pairs. Setting aside the mass of any product neutrinos, which represent released energy which generally continues to be unavailable, the end result of annihilation is a release of energy available to do work, proportional to the total matter and antimatter mass, in accord with the mass-energy equivalence equation,E=mc2. Q.7 Statements: 1) Reverse osmosisis used for removing molecules and ions from solutions and for production of potable water 2) Membrane sizes, membrane pore size, temperature, operating pressure, and membrane surface area are the factors that affect water purification through reverse osmosis Codes: A) Only 1 B) Only 2 C) Both are correct D) Both are incorrect Ans. C Reverse osmosis (RO) is a water purification technology that uses a semipermeable membrane. This membrane technology is not properly a filtration method. In reverse osmosis, an applied pressure is used to overcome osmotic pressure, a colligative property, that is driven by chemical potential, a thermodynamic parameter. Reverse osmosis can remove many types of molecules and ions from solutions, and is used in both industrial processes and the production of potable water. The result is that the solute is retained on the pressurized side of the membrane and the pure solvent is allowed to pass to the other side. To be "selective", this membrane should not allow large molecules or ions through the pores (holes), but should allow smaller components of the solution (such as the solvent) to pass freely. Q.8 Which of the following are the limitations of the Thorium nuclear power ? 1) Breeding will be slow and requires extensive reprocessing 2) Approval for business and government support is needed & it includes expensive testing, analysis and licensing work is first required 3) There is a higher cost of fuel fabrication Codes: A) 1 & 3 B) 2 & 3 C) 1 & 2 D) 1,2,3 Ans. D Q.9 Which among the following are the advantages of the Thorium ? 1) The thorium fuel cycle offers enormous energy security benefits in the long-term 2) Its potential for being a self-sustaining fuel without the need for fast neutron reactors 3) Thorium is considered as the "most abundant, most readily available, cleanest, and safest energy source on Earth 4) There is much less nuclear waste Codes: A) 1,3,4 B) 2,3,4 C) 1,2,3,4 D) 1,2,3,4 Ans. D Q.10 Which among the following are the sources of Arsenic Poisoning ? 1) Agricultural run off 2) Improperly disposed arsenical chemicals 3) Mining 4) Contamination from runoff from wood preservatives Codes: A) 2 & 4 B) 2 & 3 C) 1,2,4 D) 1,2,3,4 Ans. D Q.11 Which among the following are the pollinating agents ? 1) Birds 2) Bats 3) Honeybees 4) Butterflies Codes: A) 1 & 2 B) 3 & 4 C) 1 & 4 D) All are correct Ans. D Q.12 In context with the Virtual Private Network, which among the following statements are correct ? 1) It enables a computer to send and receive data across shared or public networks 2) It is created by establishing a virtual point-to-point connection 3) It allows securely access Codes: A) 1 & 3 B) 2 & 3 C) 1 & 2 D) 1,2,3 Ans. D A virtual private network connection across the Internet is similar to a wide area network (WAN) link between sites. From a user perspective, the extended network resources are accessed in the same way as resources available within the private network VPNs securely connect geographically disparate offices of an organization, creating one cohesive network.