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This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
How is heavy water prepared ? Compare its physical properties with those of ordinary water. |
Answer» SOLUTION :HEAVY WATER is prepared by prolonged electrolysis of water. Its physical properties are as under:  
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| 2. |
How is heavy prepared ? Compare its physical properties with those of ordinary water. |
| Answer» SOLUTION :Heavy WATER is PREPARED by prolonged ELECTROLYSIS of water. For comparison of physical properties of heavy water with those of ordinary water. | |
| 3. |
How is gypsum synthesized? |
| Answer» Solution :Gypsum can also be synthesized from coal-fired POWER plants, as a bv. DESULFURIZATION. The process of scrubbing sulfur from flue gases produced wi RESULTS in the production of several by-products, including gypsum. | |
| 4. |
How is excessive content of CO_(2) responsible for global warming ? |
| Answer» Solution :In ATMOSPHERE, the concentration of `CO_2` is constant due to `CO_2` cycle. However, when the concentration of `CO_2` in the atmosphere increases beyond a certain level due to man MADE activities, the excess `CO_2` absorbs heat radiated by the earth. Some of it escapes into the atmosphere while the remaining PART of it is radiated back to the surface of the earth. This increases the temperature of the earth and LEADS to global warming. The effect is CALLED greenhouse effect. | |
| 5. |
How is excessive content of CO_2 responsible for global warming ? |
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Answer» SOLUTION :`CO_2` is very essential gas. The AMOUNT of `CO_2` in atmosphere is increases by increasing combustion of crude FUEL and the decomposition of lime stone which is utilize in PRODUCTION of cement. This results in an INCREASE in the atmospheric temperature, there by causing global warming. |
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| 6. |
How is ethene prepared from bromoethane? |
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Answer» Solution :`C_(2)H_(5)-Br+underset("ALCOHOLIC")(KOH)toC_(2)H_(4)+KBr+H_(2)O` Ethyl bromide reacts with alco. KOH to form ETHENE. |
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| 7. |
How is dihydrogen prepared from water by usinga reducing agent? |
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Answer» Solution :Dihydrogen is prepared from WATER by the action of REACTIVE metal like Na or K which is a strong REDUCING agent due to low ionisation enthalpy. `2Na+2H_(2)O to 2NaOH+H_(2)` `2K+2H_(2)O to 2KOH+H_(2)` |
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| 8. |
How is degree of dissociation related with concentration terms and Ka, for weak electrolyte. |
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| 9. |
How is diborane prepared ? |
| Answer» Solution :`2BF_(3) (g) + 6LiH(s) overset(450 K) rarr B_(2)H_(6)(g) + 6 LIF(s)` or `2NaBH_(4) + I_(2)overset("DIGLYME")rarr B_(2)H_(6) + Nal + H_(2)` | |
| 10. |
How is degree of dissociation and degree of association are related with van't Hoff factor ? |
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Answer» Solution :The degree of DISSOCIATION or association can be related to van.t Hoff factor (i) USING the FOLLOWING RELATIONSHIP `alpha _("dissociation") =(i-1)/(n-1), alpha _("association") = ((1-i)n)/(n-1)` when n = number of solute particles |
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| 11. |
How is D_(2)O_(2) prepared ? |
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Answer» Solution :`D_(2)` is PREPARED by DISTILLATION of POTASSIUM persulphate`(K_(2)S_(2)O_(8))` with `D_(2)O` . `underset("Pot. Persuphate")(K_(2)S_(2)O_(8))+ 2D_(2)O overset("Distil")to D_(2)O_(2) + 2KDSO_(4)` |
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| 12. |
How is boron obtained from borax ? Give chemical equations with reaction conditions and its reaction with HCI. |
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Answer» Solution :`Na_(2)B_(4)O_(7).10H_(2)O+H_(2)SO_(4) rarr Na_(2)SO_(4) rarr Na_(2)SO_(4)+ underset ("Tetraboric acid") (H_(2)B_(4)O_(7)) +10H_(2)O` `H_(2)B_(4)O_(7)+5H_(2)Orarr underset ("Boric acid")(4H_(3)BO_(3))` `2H_(3)BO_(3) overset ("RED HEAT")rarr underset("Boric oxide")(B_(2)O_(3))+3H_(2)O` `B_(2)O_(3)+3Mg overset ("heat ")rarr2B+3MgO` with dry HCI , `B_(2) H_(6)` evolves `H_(2)` gas `B_(2) h_(6) + underset(("dry")) (HCI) rarr B_(2)H_(5)CI+H_(2)` |
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| 13. |
How is bonding molecular orbitals in a molecule of hydrogen different from its antibonding molecular orbital? |
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Answer» SOLUTION :Bonding molecular orbital has LOWER energy and contains 2 electrons while antibonding molecular orbital has HIGHER energy and is empty. |
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| 14. |
How is bond order related to the stability of a molecule ? |
| Answer» SOLUTION :HIGHER the bond order, GREATER is the STABILITY . | |
| 15. |
How is bond strength related to bond order? |
| Answer» SOLUTION :GREATER the BOND ORDER,greater is the bond STRENGTH | |
| 16. |
How is bond order related to bond length of a molecular ? |
| Answer» SOLUTION :BOND LENGTH is INVERSELY proportinal to bond ORDER . | |
| 17. |
How is benzene directly converted to chlorobenzene ? |
Answer» SOLUTION :
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| 18. |
How is barium peroxide prepared? |
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Answer» Solution :BARIUM PEROXIDE is PREPARED by heating monoxides with OXYGEN at high temperature. `underset("Barium oxide")(2BaO+)O_(2)OVERSET(/_\)tounderset("Barium peroxide")(2BaO_(2))` |
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| 19. |
How is aniline purified ? |
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| 20. |
How is an electron identified in an atom ? |
| Answer» Solution :ELECTRON of an atom is identified by its FOUR quantum NUMBERS. | |
| 21. |
How is Alkane prepared from Grignard reagent? |
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Answer» Solution :`CH_(3)MgX+HOH RARR CH_(4) Mg (OH)X.` Water would protonate the grignard reagent and destroy the grignard reagent, because the grignard carbon ATOM is HIGHLY nucleophilic. This would form a hydrocarbon. Therefore to MAKE a grignard solution, only ether is the best SOLVENT and water or alcohol are not llSed for that purpose. |
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| 22. |
How is alkane prepred from Kolbe's electrolytic method? |
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Answer» Solution :A CONCENTRATED sodium salt of a CARBOXYLIC ACID is electrolysed. The ALKANE is formed at the anode as one of the products. This process is called Kolb's electrolysis. Eg: 
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| 23. |
How is Alkane perpared from Grignard reagent ? |
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Answer» Solution :`CH_(3)Mgl+HO-H to CH_(4) +Mgl(OH)` `CH_(3)Mglunderset("Ethyla alcohol")(+C_(2)H_(5)OH)OVERSET(Delta)tounderset("METHANE")(CH_(4))+Mgl(OC_(2)H_(5))` |
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| 24. |
How is alkaline silver nitrate represented? |
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Answer» Solution :SILVER nitrate FORMS silver hydroxide with alkali. `AgNO_(3)+ NaOHto AgOH+NaNO_(3)` Silver hydroxide is less stable and is transformed into brown-black silver oxide. `2AgOHunderset(-H_(2)O)rarrAg_(2)O` Alkaline silver nitrate is CALLED Tollen.s reagent. |
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| 25. |
How is acid rain formed? Explain its effect. |
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Answer» Solution :(i) Rain water has,a pH of 5.6 due to the dissolution of `CO_(2)` into it. Oxides of sulphur and nitrogen in the atmosphere may be absorbed by droplets of water that make up the clouds and get chemically converted into SULPHURIC acid and nitric acid. Due to this the pH of rain water drops below the level of 5.6. Hence it is called acid rain. (ii) Acid rain is a by-product of sulphur and Nitrogen oxides in the atmosphere. Burning of fossil fuels in power stations, furnaces and petrol, diesel in motor engines produce `SO_(2)` and `NO_(2)` gases. They are converted into `H_(2)SO_(4)` and `HNO_(3)` by the reaction with oxygen and water. (iii) `2SO_(2) + O_(2)+2H_(2)O rarr 2H_(2)SO_(4)` `4NO_(2)+O_(2) + 2 H_(2)O rarr 4HNO_(3)` Harmful effects of acid rain 1) Acid rain causes damage to buildings made us of marbles. This attack on marble is TERMED as stone leprosy.`CaCO_(3) + H_(2)SO_(4) rarr CaSO_(4) rarr CaSO_(4) + H_(2)O + CO_(2) UARR` (ii) Acid rain affects plant and animal life in aquatic ecosystem. (iii) It is harmful for agriculture, as it dissolves in the earth and removes the nutrients needed for the growth of plants. (iv) It corrodes water pipes RESULTING in the leaching of HEAVY metals such as iron, lead and copper into drinking water which have toxic effects. (v) It causes respiratory ailment in humans and animals. |
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| 26. |
How is acid rain formed ? Explain its effect. |
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Answer» `2SO_(2) + O_(2) + 2H_(2)O to 2H_(2) SO_(4)` `4NO_(2) +O_(2) + 2H_(2) O to 4HNO_(3)` The pH of rain water drops to 5: 6 and hence its is called acid rain . Harmful effects of acid rain : Some harmful effects are DISCUSSED below . (i) Acid rain causes extensive damage to buildings and structural materials of marbles. This attack on marble is termed as Stone leprosy. `CaCO_(3) + H_(2) SO_(4) to CaSO_(4) + H_(2)O + CO2uarr` (ii)Acid rain affects plants and animal life in aquatic ecosystem. (iii)It is harmful for agriculture, trees and plants as it dissolves and removes the nutrients needed for their growth. (iv)It corrodes water pipes resulting in the leaching of heavy metals such as iron, lead and copper into the drinking water which have toxiceffects . (v)It causes RESPIRATORY AILMENT in humans and animals . |
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| 27. |
How is acetylene converted to 3-hexyne ? |
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Answer» Solution :Acetylene is treated with sodium metal to get disodium ACETYLIDE which on treatment with ETHYL bromide, 3-hexyne is formed. `HC-=CH+2NatoNaC-=CNaoverset(2C_(2)H_(5)Br)toCH_(3)CH_(2)C-=C CH_(2)CH_(3)+2NaBr` |
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| 28. |
How is a gas-solution equilibrium exist? |
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Answer» SOLUTION :When a gas dissolves in a liquid under a given pressure, there will be an EQUILIBRIUM between gas molecules in the GASEOUS state and those dissolved in the liquid. Example : In carbonate beverages the following equilibrium exists. `CO_(2) (G) hArr CO_(2)` (solution) |
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| 29. |
How ionic nature of trihalides of IIIA elements is related to their a cidic character? |
| Answer» Solution :The more the covalent nature, the more is the deficiences and more is the acidic nature. Similarly the bigger the size of halogen ATOM, the less is the back bonding and more is the Lewis acidic nature. Therefore, IONIC nature of the TRIHALIDES of IIIA group elements is inversely RELATED to their acidic nature. | |
| 30. |
How gypsum occurs in nature? |
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Answer» Solution :Gypsum beds were formed due to the evaporation of WATER from the massive prehistoric sea BASINS When water evaporates, the minerals present in it become concentrated and crystallized. (iii) Gypsum is formed, due to evaporation, sulphur present in water BONDS with OXYGEN to form a sulphate. The sulphate then combines with CALCIUM and water to form gypsum. |
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| 31. |
How fluoride in the tooth paste protects teeth against decay ? |
| Answer» SOLUTION :The fluoride ions make the enamel on the TEETH much HARDER by converting HYDROXY patite (enamel on the SURFACE of the teeth) into much harder fluorapatite. | |
| 32. |
How fast is an electron moving if it has a wavelength equal to the distance it travels in one second? |
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Answer» `SQRT((m)/(h))` Given `LAMDA = v`. HENCE, `lamda = (h)/(mv)` becomes `v = (h)/(mv)` or `v^(2) = (h)/(m) or v = sqrt((h)/(m))` |
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| 33. |
How fast must a 5 4 g tennis ball travel in order to have a de Broglie wavelength that equal to that of a photon of green light 5400overset(0)(A)? |
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Answer» SOLUTION :m=mass of TENNIS ball =`54 g =5.4xx10^(-2)kg.` `gamma`=DE Broglie wacelength`=5400overset(0)(A)=5400xx10^(-10)m` `gamma=4/(mV)` `V=h/(gamma.m)` `(6.626xx10^(-34))/(5400xx10^(10)xx5.4xx10^(-2))` `=(6.626xx10^(-34)xx10^(10)xxcancel(10^(2)))/(cancel(5400)x5.4)` `=(6.626xx10^(-24))/(54xx5.4)` `=(6.626xx10^(-24))/(291.6)` `=2.27xx10^(26)m` |
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| 34. |
How fast is an electron moving if it has a wavelength equal to the distance it travels in one second? (mass of electron = 9.1 xx 10^(-31)kg) |
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Answer» SOLUTION :Here `v = lamda`. HENCE, `lamda = (H)/(mv) " gives" v^(2) = (h)/(m)` or `v = sqrt((h)/(m)) = sqrt((6.626 xx 10^(-34))/(9.1 xx 10^(-31))) = 2.698 xx 10^(-2) ms^(-1)` |
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| 35. |
How ethane is prepared by dehydrohalogenation? Write equation. |
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| 36. |
How entropy change in the following process. (a) boiling of egg , (b) stretching of rubber: (c ) Formation of micells (d)CH_(3)COOH_((aq)) Leftrightarrow CH_(3)COO_((aq))^(-)+H_((aq))^(+). |
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Answer» Solution :a) During the boiling of egg, protein is DENATURED. As a result irregularity increases and entropy increases. b) As a result of STRETCHING of RUBBER, irregular coiled structure becomes REGULAR. Hence entropy decreases, c) Before formation of micells by SOUP or detergent, each molecule is hydrated. After the formation of micells, old solvated water molecules are scaterd now. As a result entropy increases during formation micells. (d) `CH_(3)COOH_((aq)) Leftrightarrow CH_(3)COO_((aq))^(-)+H_((aq))^(+)` when compared with reactant, products are more hydrated. Hence orderlyness increases in the ionisation of acetic acid and entropy decreases. |
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| 37. |
How electronegativity vary down the group in the periodic table? |
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| 38. |
How eill you prepare Lassaigne's extract ? |
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Answer» Solution :(i) A small piece of NA dried by pressing between the folds of filter paper is taken in a fusion tube and it is gently heated. When it melts to a shinig globule, a pinch of organic compound is ADDED. (ii) The tube is heated till reaction ceases and become red hot. Then it is PLUNGED in 50 ML of distilled water taken in a china dish and bottom of the tube is broken by striking it against the dish. (iii) The contents of the dist is boiled for 10 MINUTES and then it is filtered. The filtrate is known as Lassaigne.s extract. |
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| 39. |
How dry ice is produce ? Mention its uses. |
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Answer» Solution :Carbon dioxide can be OBTAINED as a solid in the form of dry ice by allowing the liquefied `CO_2` to expand rapidly. Dry ice is used as a REFRIGERANT for ice-cream and frozen FOOD. |
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| 40. |
How does water react with(i) SiCI_(4)(ii) P_(4)O_(10) |
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Answer» Solution :(i) Water reacts with Sil, to give silica `SiCI_(4)$H_(2)OtoSi(OH)_(4)+4HCI` `SI(OH)_(4)overset(Delta)tounderset(Silice)(SiO_(2))+2H_(2)O` (ii) Water reacts with P,0, to give ortho phosphoric acid. `P_(4)O_(10)+6H_(2)Otounderset("Ortho phosphoric acid")(4H_(3)PO_(4))` |
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| 41. |
How does water add on to propyne? Give the equations and explain. |
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Answer» Solution :`CH_(3)-C-=CH+HOHunderset(He^(2+))overset(H_(2)SO_(4))to[CH_(3)-underset(OH)underset(|)C=CH_(2)]toC_(3)-underset(O)underset(||)C-CH_(3)` In the first setp, water ADDS on to propyne following Markovnikov rule to form propane-2ol. Being an enol, it is unstable and UNDERGOES TAUTOMERISATION to form stable propanone. |
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| 42. |
How does velence bond theory, explain the existence of H_(2) but non-existence of H_(2)? |
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Answer» Solution :According to VALENCE bondtheory, a covalent bond is FORMED by OVERLAP of half-filled ATOMIC orbitals : H-atoms have half-filled orbitals `(1s^(1))` but He atoms have fully filled orbitals `(1s^(2))`. |
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| 43. |
How does the troposphere get demaged by oxides of carbon ? |
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Answer» Solution :(i) Effacts of carbon monoxide : Carbon monoxide (CO) is one of the most serious air pollutants. It is a colourless and odourless gas. It has ability to block the DELIVERY of oxygen to the organs and tissues so it is also highly poisonus for the living organisms. Because of incomplete combustion of carbon, carbon monoxide (CO) is produced. Automobile exhaust also RELEASED carbon monoxide into the air. Incomplete combustion of coal, firewood, petrol, etc. are also responsible for the production of carbon monoxide. Carbon monoxide binds hemoglobin to from carboxyhemoglobin. This complex is 300 times more stable than oxygen-hemoglobin complex. In blood, when the concentration of carboxyhemoglobin reaches about 3-4% than the oxygen carrying capacity of blood is greatly reduced and because of this headche weak eyesight nervousness and cardiovascular disorder take place. So people are advised not to smoke. If pregnant women who have the habit of smoking the increased CO level in blood may induce premature birth, spontaneous abortions and deformed BABIES. (ii) EFFECT of carbon dioxide : Carbon dioxide `(CO_2)` is released into the atmosphere by respiration, burning of fossil fuels for energy, and by decomposition of limestone during the manufacture of cement. It is also emitted during volcanic eruptions. Carbon dioxide gas is confined to troposphere only. Normally it forms about 0.03 per cent by volume of the atmosphere. With the increased use of fossil fuels, a large amount of carbon dioxide gets released into the atmosphere. Excess of `CO_2` level in the air maintains by planting green plants. Green plants require `CO_2` for photosynthesis and they emit oxygen, during this process. Because of this the level of `CO_2` and `O_2` is maintained. Deforestation and burning of fossil fuel increases the `CO_2` level and disturb the balance in the atmosphere. The increased amount of `CO_2` in the air is mainly responsible for global WARMING |
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| 44. |
How does the surface tension of a liquid vary with increase in temperature ? |
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Answer» Remains same Note : Surface tension of a liquid is said to be the force acting at right angles to the surface along 1 cm length of the surface. Units of surface tension are DYNE per cm (or NEWTONS per metre i.e., `Nm^(-1)` in the SI systems). |
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| 45. |
How does the shielding effect caused by inner electrons affect the ionisation energy? |
| Answer» Solution :As we move down a group , the NUMBER of inner shell electron increases WHICHIN turn increases the repulsive force EXERTED by them on the valence electrons , thus decreases the nucleus. THEREFORE the ionisation eneergy decreases. | |
| 46. |
How does the ozone gets add on to the C-=C? |
Answer» Solution :Ozone adds to carbon-carbon triple bond of ALKYNES to form ozonides. The ozonides are HYDROLYZED by WATER to form carbonyl compounds. The hydrogen peroxide `(H_(2)O_(2))` formed in the reaction may oxidise the carbonyl COMPOUND to carboxylic acid.  
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| 47. |
How does the non-degradable industrial solid waste is disposaled ? |
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Answer» Solution :The disposal of non-degradable industrial solid WASTES, if not done by a proper and suitable method it may cause serious THREAT to the ENVIRONMENT. Nowadays, fly ash and slag from the steel industry are utilised by the cement industry. LARGE quantities of toxic wastes are usually destroyed by controlled incineration, where as small quantities are burnt along with factory garbage in open BINS. |
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| 48. |
How does the ozone gas become ? |
| Answer» Solution :When UV radiations acting on DIOXYGEN `(O_2)` molecules, the UV radiations split APART molecular oxygen into FREE oxygen atoms. These oxygen atoms combine with the molecular oxygen to form ozone. | |
| 49. |
How does the nature of oxides vary in the third period? |
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| 50. |
How does the metallic and non metallic character vary on moving from left to right in a period ? |
| Answer» Solution :Moving from left to RIGHT metallic CHARACTER decreases and non metallic character increases. It is due to the increase in IONISATION enthalpy and electron gain enthalpy from left to right. | |