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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 5351. |
How is the concentration of hydronium ions (H_(3)O^(+)) affected when a solution of an acid is diluted ? |
| Answer» SOLUTION :When an acid is diluted , the CONCENTRATION of hydronium IONS `(H_3O^(+) ) ` PER unit volume decreases . This means that the strength of the acid decreases. | |
| 5352. |
How is the concentration of hydronium ions (H_(3)O^(+)) affected when a solution of an acid is diluted? |
| Answer» SOLUTION :When a solution of an acid is diluted, the concentration of hydronium ion `(H_(3)O^(+))` per unitvolume DECREASE. | |
| 5353. |
How is the chemical reaction written ? Explain it with suitable example. |
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Answer» Solution :The burning of magnesium RIBBON in presence of OXYGEN forms magnesium oxide. The reaction is conveniently described by a chemical EQUATION as shown below `underset("REACTANTS")(ubrace(Mg+O_(2))) to underset("Product")(ubrace(MGO))` In the equation, Mg and `O_(2)` undergo chemical reaction are called reactants, and Mgo is known as product which is obtained at the end of the reaction. Reactants are always written on the left side and products are mentioned on the right side of the arrow in the chemical equation. The sign `to` is put between the reactants and products. If more than one reactants are involved in the reaction, then + sign is written between them. Similarly, if more than one products are formed, then also, + sign is placed between them. |
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| 5354. |
How is the amount of urine produced regulated ? |
| Answer» Solution :The amount of URINE PRODUCED is regulated by reabsorption of WATER and some of the dissolved subtances into the blood through bloodcapillaries surrounded by the tabules of nephrons. The amount of urine produced DEPENDS upon how MUCH exess water is present in the body and how much of dissolved salts are to be excreted. | |
| 5355. |
How is silicon carbide prepared? Write one of its uses. |
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Answer» Solution :Heating the mixture of SILICON and COKE in an electric FURNACE. `SI + C Rightarrow SiC` Silicon carbide is used in : (i) Cutting and grinding tools, (ii) Polishing granite. |
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| 5356. |
How is Plaster of Paris prepared ? Why is temperature control necessary during its preparation ? How does it react with water ? |
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Answer» Solution :It is prepared by HEATING gypsum `(CaSO_4. 2H_2O)` at 373K ina KILN . `underset("Plaster of Paris")(CaSO_4. 2H_2O) to underset(373K)overset("Heat")to underset("Gypsum")(CaSO_4. 1/2 H_2O) + 1""1/2 H_2O ` `underset("Gypsum")(2CaSO_4 . 2H_2O) overset(373K) to underset("Plaster of Paris ")((CaSO_4)_2. H_2O) + 3H_2O ` It may be noted that the temperature should be controlled carefully. It should not be allowed to rise above 425 K, because the whole of water is lost and anhydrous calcium sulphate `(CaSO_4)` is produced. It is CALLED dead burnt plaster. It has no such property as that of Plaster of Paris. When mixed with water, it forms a paste which sets into a hard mass. This is called setting of Plaster of Paris. The setting of Plaster of Paris is due to its hydration into gypsum. `(CaSO_4)_2. H_2O + 3H_2O to underset("(Gypsum)")(CaSO_4. 2H_2O)` |
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| 5357. |
How is plaster of paris prepared? |
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Answer» SOLUTION :Plaster of Paris is prepared by heating gypsum to a TEMPERATURE of `100^@C` . The following reaction takes place ` CaSO_4. 2H_2O overset(100^@C)(to) CaSO_(4) 1/2H_2O+ 1(1)/(2) H_2O` : On mixing with WATER, it react to a hard mass to form gypsum again i.e, the reverse reaction takes place. |
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| 5358. |
How is plaster of Paris chemically different from Gypsum ? How can they be inter -converted ? Write two uses of plaster of paris. |
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Answer» Solution :Plaster of paris chemically is `CaSO_(4) ½H_(2)O` Gypsum is `CaSO_(4).2H_(2)O` On heating gypsum at 373 K, it loses water molecule and BECOMES calcium sulphate hemihydrate. `CaSO_(4) ½H_(2)O`. Again on treating with water plaster of paris becomes gypsum. `underset("Plaster of paris")(CaSO_(4). ½H_(2)O) + 1½ H_(2)O rarr underset("Gypsum")(CaSO_(4).2H_(2)O)` `underset("Gypsum")(CaSO_(4).2H_(2)O) underset(373 K)OVERSET("HEAT")rarr underset("Plaster of paris")(CaSO_(4). ½H_(2)O) + H_(2)O` |
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| 5359. |
How is methanol converted to methanoic acid ? |
| Answer» Solution :`UNDERSET("METHNOL")(CH_(3)OH)underset(Alk. KMnO_(4))overset((O))rarr underset("Methanoic ACID")(HCOOH)` | |
| 5360. |
How is hydrogen chloride gas dried ? |
| Answer» Solution :Hydrogen chloride GAS is DRIED by PASSING it through a guard TUBE containing anhydrous calcium chloride. | |
| 5361. |
How is glacial acetic acid different from acetic acid given in a lab? Write its one characteristic which gave it its name. |
| Answer» SOLUTION :Glacial acetic acid is pure acetic acid WHOSE melting point is 290 K and it freezes during winter like a GLACIER, hence the NAME. The acetic acid in a lab is diluted acetic acid called vinegar WHEREAS glacial acetic acid is 100% pure. | |
| 5362. |
How is ethyne converted to tetrabromoethane |
| Answer» SOLUTION :`HC -= CH OVERSET(2Br_2)(to) Br_2HC - CHBr_2` | |
| 5365. |
How is ethanol obtained for commercial use? |
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Answer» Solution :When ethene is heated with concentrated sulphuric acid at `75^(@)C` (348 K), and treated with water, ethanol is produced. `UNDERSET("Ethene")(CH_(2)=CH_(2))+underset("Water")(H-OH) OVERSET(H_(2)SO_(4))to underset("Ethanol")(CH_(3)-CH_(2))-OH` |
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| 5366. |
How is ethanol obtained from ethene? |
| Answer» SOLUTION :`underset("ethene")(H_2C= CH_2(G)) + underset("steam")(H_2O(g)) overset("PHOSPHORIC ACID on silica, " 300^@" , 70 atm ")(to) underset("ethenol")(CH_3CH_2OH)` | |
| 5367. |
How is ethanol manufactured from sugarcane? |
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Answer» Solution :Fermentation method can be used to obtain ethanol from sugarcane. Actually, in industries `C_(2)H_(5)OH` is prepared by the fermentation of molasses, which is a by product obtained during manufacture of sugar from sugarcane. It is converted into ethanol by following steps. (i) Dilution of molasses (II) Addition of nitrogen source (iii) Addition of YEAST (iv) Distillation of wash Chemical reactions: `UNDERSET("sugar")(C_(12)H_(22)O_(11))+H_(2)Ooverset("Invertase")rarrunderset("Glucose")(C_(6)H_(12)O_(6))+underset("Fructose")(C_(6)H_(12)O_(6))` `underset("Glucose or Fructose")(C_(6)H_(12)O_(6))OVERSET("Zymase")rarrunderset("Ethanol")(2C_(2)H_(5)OH)+2CO_(2)` |
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| 5368. |
How is ethanol converted to ethene using a solid as dehydrating agent other than conc. H_2SO_4? Give only balanced equations. |
| Answer» SOLUTION :`underset("ETHANOL")(C_2H_5OH) OVERSET("alumina"// 350-450^@C)(to) underset("ETHENE")(H_2C = CH_2) + underset("water")(H_2O)` | |
| 5369. |
How is ethanol manufactured from sugarcane ? |
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Answer» Solution :Ethanol Manufacture : (i) Ethanol is manufactured in industries by the fermentation of molasses, which is a by-product obtained during the manufacture of sugar from sugarcane. (ii) Molasses is a DARK coloured syrupyliquid left after the crystallization of sugar from the concentratedsugarcanejuice . (iii) Molassescontain about 30% of sucrose , whichcannot be separatedby crystallization .It is converted into ethanol by the following steps : a) Dilution of molasses : Molassesis firstdiluted with waterto bringdown the concentration of sugar to about 8 to 10% . b) Addition of Nitrogen source : (i) Molassesusually containsenough nitrogeneous matterto act as food for yeast during the fermentationsprocess. (ii) If the nitrogen contentof the molasses is pooer , it may be fortified by the addition of ammonium sulphate or ammonium phosphate . (C) Addition of Yeast : The solution obtained in step . Is collectedin large ' fermentation tanks' and yeastis added to it . The mixtureis kept at about 303 K for a few days . During this period , the enzymes invertase and zymasepresent in yeast , BRING about the conversion of sucrose into ethanol . `underset("sugar")(C_(12)H_(22)O_(11))+H_2O overset("invertase")to underset("GLUCOSE")(C_6H_(12)O_6)+ underset("fructose")(C_6H_(12)O_6)` ` underset("glucose or fructose ")(C_6H_(12)O_6) overset("zymase")to underset("ethanol")(2C_2H_5OH)+2CO_2 ` The fermentedliquidis technicallycalled wash . d) Distillation of 'Wash' : (i) The fermented liquid (i.e. wash) , containing15 to 18 percent ALCOHOL , is now subjected to fractional distillation. (ii) The main fraction drawn in an aqueoussolutionof ethanol which contain 95.5% of ethanoland 4.5% of water . This is called rectified spirit . |
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| 5370. |
How is ethanoicacid prepared from ethanol ? Give the chemical equation . |
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Answer» Solution :By the oxidation of ethanolin the presenceof alkaline POTASSIUM permanganate or acidified potassium DICHROMATE. `underset("Ethanol")(CH_3CH_2OH) underset(2[O]) OVERSET(KMnO_4//OH^(-))to underset("Ethanoic ACID ")(CH_3COOH)+H_2O` |
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| 5371. |
How is ethanoic acid prepared from ethanol? Give the chemical equation. |
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Answer» SOLUTION :Ethanol acid can be prepared by oxidation of ethanol in the presence of alkaline POTASSIUM permanganate of ACIDIFIED potassium dichromate. `CH_(3)CH_(2)OHunderset(2[O])overset(KMnO_(4)|OH^(-))rarrunderset(("Ethanoic acid"))(CH_(3)COOH+H_(2)O)` |
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| 5372. |
How is ethanoic acid prepared from ethanol? |
| Answer» SOLUTION :`UNDERSET("ETHANOL")(C_2H_5OH) overset([O])(to) underset("ethanal")(CH_3CHO) overset([O])(to) underset("ETHANOIC acid")(CH_3COOH)` | |
| 5373. |
How is corrosion different from rusting ? |
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Answer» Solution :Corrosion is OBSERVED in all the metals, when EXPOSED to air, and a layer of compound is formed due to REACTION of metal with moisture, acid and gases present in atmosphere. Rusting is a process in which iron reacts with air and moisture to FORM brownish red coloured powder called RUST. Due to corrosion, metal lose their lustre and become dull while due to rusting iron metal is slowly destroyed. |
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| 5374. |
How is caustic soda obtained? Mention its uses. |
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Answer» SOLUTION :Caustic Soda (NaOH) is manufactured by electrolysis of AQUEOUS solution of SODIUM chloride (Brine). This method is called chloroalkali process. `2NaCl (AQ) + 2H_2O (l) to 2NAOH(aq) + Cl_2 + H_2` Sodium hydroxide is used in making soaps and detergents, degreasing metals, paper making and artificial fibers like rayon |
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| 5375. |
Howis bleaching powder prepared ? Why does bleaching powder (i) Smell strongly of chlorine ? (ii) not dissolve completely in water ? |
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Answer» Solution :Bleaching powder is prepared by the action of `Cl_(2)` on DRY SLAKED lime . `Ca(OH)_2 + Cl_2 rarr CaOCl_2+H_2O` Bleaching powder SMELLS strongly of chlorine because it is loosely bound to slaked lime. Carbon dioxide present in the air combines with bleaching powder leberating chlorine. `CaOCl_(2) + CO_2 rarr CaCO_2 + Cl_2 uarr` Bleaching powder reacts with water as under : `CaOCl_(2) + CO_2 rarr Ca(OH)_2 + Cl_2` `Ca(OH)_2 + underset("(Form air)")(CO_2) rarr underset("CARBONATE")underset("Calcium")(CaCO_3 + H_2O)` |
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| 5376. |
How is Bauxiteare concentrated ? |
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Answer» Solution :(i) Chemical method or Leachingmethod is EMPLOYED when the oreis in a very pure form . (ii) The ORE is TREATED with a suitablereagent such that the ore is solublein its butthe IMPURITIESARE not . (iii) The impuritiesare removed by FILTRATION . (iv) The solution of the ore, i.e., the filtrate is treated with a suitablereagentwhichprecipitatesthe ore . |
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| 5377. |
How is baking powder formed ? List any two uses of baking powder. |
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Answer» Solution :For making baking powder, a MILD edible acid such as TARTARIC acid is added to baking soda (sodium hydrogen carbonate). This mixture is baking soda. when baking powder is heated or mixed in water, the following reaction takes place - `NaHCO_(3) + H^(+) rarr CO_(2) + H_(2)O +` Sodium salt of acid (Drom any acid) Uses of baking powder. (a) Carbon dioxide produced during the reaction causes bread or cake to rise making the soft and spongy. (b) It is also an ingredient in antacids. Being alkaline, it neutralises excess acid in the STOMACH and provides relief. (c ) It is also used in soda-acid FIRE extinhuishers. |
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| 5378. |
How is Average atomic mass calculated ? |
| Answer» SOLUTION :Average atomic MASS of an ELEMENT is calculated by adding the masses of its isotopes, each multiplied by their NATURAL abundance on the Earth. | |
| 5379. |
How is an ionic bond formed? |
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Answer» SOLUTION :An ionic bond is FORMED when one of the ATOMS can DONATE ELECTRONS to achieve the inert gas electronic configuration and other atom needs electrons to achieve the inert gas electronic configuration. |
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| 5380. |
How is a chemical equation written ? Illustrate with an example. |
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Answer» Solution :A chemical equation is written using chemical SYMBOLS to indicate the reactants and PRODUCTS, which are connected using a forward ARROW. Multiple reactants and products are connected using a plus (.+.) sign. e.g. : When silver chloride is placed sunlight, it decomposes into silver metal and CHLORINE gas. `2AgCl(s)overset("sunlight")(to)2Ag(s)+Cl_(2)(g)`. |
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| 5381. |
How ethanol reacts with the following ? Give chemical reactions. (a) Acidified Potassium dichromate (b) Hot conc. H_(2)SO_(4) (c ) Sodium (Na). |
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Answer» Solution :Properties of alcohols (A) Physicial properties 1. The lower members of alcohols are colourless, volatile liquids having typical alcoholic smell and burning taste. 2. Lower alcohols are completely soluble in water. However, the solubility decreases with increase in molecular mass. 3. The boilng points of alcohols are higher than those of alkanes of comparable molecular masses. 4. The common alcohols are lighter than water. B. Chemical Properties. 1. Action with sodium. Alcohols react with sodium metal to form sodium alkoxide and hydrogen gas is liberated. For example, `underset("Methanol")(2CH_(3)OH) + 2NA rarr underset("Sodium methoxide")(2CH_(3)ONa) + H_(2)` `underset("Ethanol")(2C_(2)H_(5)OH) + 2Na rarr underset("Sodium ethoxide")(2C_(2)H_(5)ONa) + H_(2)` 2.Combustion. Alcohols burns readily in air and PRODUCE carbon dioxide, water and heat. For example. `underset("Methanol")(CH_(3)OH) + O_(2) rarr CO_(2) + 2H_(2)O + "Heat"` `underset("Ethanol")(C_(2)H_(5)OH) + 3O_(2) rarr 2CO_(2) + 3H_(2)O + "Heat"` 3. Oxidation. Alcohols are easily oxidised to corresponding carboxylic acids by oxidising agents such asacidified potassium dichromate. For example, `underset("Methanol")(CH_(3)OH) + 2[O] overset(K_(2)Cr_(2)O_(7), H_(2)SO_(4))rarr underset("Methanoic acid")(HCOOH) + H_(2)O` `C_(2)H_(5)OH + 2[O] overset(K_(2)Cr_(2)O_(7), H_(2)SO_(4))rarr underset("Ethanoic acid")(CH_(3)COOH) + H_(2)O` During this reaction, the organge colour of `K_(2)Cr_(2)O_(7)` changes to green. 4. Reaction with carboxylic acids (esterification). Alcohols react with carboxylic acids in the presence of concentration sulphuric acid as catalyst to form ester which have sweet FRUIT smell. This reaction is called esterification. For example : `underset("Methanol")(CH_(3)OH) + underset("Ethanoic acid")(CH_(3)COOH) underset("Heat")overset("Conc. " H_(2)SO_(4))hArr underset("Methyl ethanoate")(CH_(3)COOCH_(3)) + H_(2)O` `underset("Ethanol")(CH_(3)CH_(2)OH) + underset("Ethanoic acid")(CH_(3)COOH) underset("Heat")overset("Conc. " H_(2)SO_(4))hArr underset("Ethyl ethanoate")(CH_(3)COOC_(2)H_(5)) + H_(2)O` Tests for Alcohols. The presence of an alcoholic group or hydroxyl group in an organic compound can be tested by the following tests : 1. Sodium metal test. Add a small piece of sodium metal of the organic compound in a dry test tube. If the bubbles of hydrogen gas are produced, it shows the presence of alcoholic group (-OH) in the organic compound. 2. Ester formation test. Warm the organic compound with acetic acid and a few drops of conc. `H_(2)SO_(4)`. A sweet smell (due to the formation of ester) indicates the presencce of alcohlolic group. |
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| 5382. |
How ethanoic acid reacts with following ? Give chemical equation :(a) Na_(2)CO_(3) (b) NaOH (c ) CH_(3)CH_(2)OH in presence of acid. |
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Answer» Solution :(a) Ethanoic acid reacts with `Na_(2)CO_(2)` to FORM sodium ethanoate, `CO_(2)`and water. `UNDERSET("Ethanoate Acid")(CH_(3)COOH) + Na_(2)CO_(3) rarr underset("Sodium ethanoate")(CH_(3)COONA) + CO_(2) + H_(2)O` (b) Ethanoic acid reacts with NAOH to give sodium ethanoate and water. `underset("Ethanoate Acid")(CH_(3)COOH) + NaOH rarr underset("Sodium ethanoate")(CH_(3)COONa) + H_(2)O` (c ) Ethanoic acid react with `CH_(3)CH_(2)OH` in the presence of acid to give ester (Ethyl ethanoate) and water. `underset("Ethanoate Acid")(CH_(3)COOH) + underset("Ethanol")(CH_(3)CH_(2)OH) OVERSET("Acid")rarr underset("Ethylethanoate")(CH_(3)COOCH_(2)CH_(3)) +H_(2)O` |
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| 5383. |
How doest nervous system differ from the endocrine system is forming control and co-ordination in animals? |
Answer» SOLUTION :
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| 5385. |
How does this tendency(electropositivity) change in a period? |
| Answer» SOLUTION :The TENDENCY of LOSE electrons (electro positivity) decreases as we go from LEFT to right along a period . | |
| 5386. |
How does the valency vary in going down a group? |
| Answer» SOLUTION : All the ELEMENTS in a GROUP have the same VALENCY. | |
| 5387. |
How does the valency vary in a period on going from left to right? |
Answer» SOLUTION :On going from left to right ALONG a period (SHORT period), the valency of elements increases from 1 to 4 and then decreases to 0 (zero).
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| 5388. |
How does the valency of elements vary a) in going down a group b) in going from left to right in a period of the periodic table. |
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Answer» Solution :a) Valency remains same in a group. B) Valency FIRST goes on increasing from LEFT to RIGHT in a period till middle of period and then drcreases |
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| 5389. |
How does the tendency of the elements to lose electrons change in the Modern Periodic Table in (i) a group, (ii) a period and why? |
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Answer» Solution :(i) INCREASES down a group. Reason: At each succeeding element down a group the number of SHELLS increases, so the distance of the valence shell from the nucleus increases. Since, the effective nuclear force of attraction decreases on the last shell, so it becomes easy for the ATOM to lose electrons. (ii) Decreases in a period from left to RIGHT. Reason : As the effective nuclear charge on the valence shell electron increases, the attraction between the valence electron and nucleus increases, so it becomes DIFFICULT to lose electrons. |
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| 5390. |
How does the tendency of the elements to lose electrons change in the Modern Periodic Table in (i) a group, (ii) a period and why? |
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Answer» Solution :(i) The tendency to lose electrons INCREASES down a group since the ATOMIC size increases and electrons EXPERIENCE less attraction towards the nucleus. (ii) The tendency to lose electrons decreases along a period since the electrons are FILLED in the same shell i.e., valence shell. Their attraction towards the nucleus increases DUE to decrease in atomic size. |
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| 5391. |
How does the surface of metal appear in their pure form? |
| Answer» Solution : METALS have SHINING surface in their PURE form. | |
| 5392. |
How does the surface of samples of metal appear? |
| Answer» SOLUTION :The SURFACE of samples of metal APPEAR DULL. | |
| 5393. |
How does the property vary in periodsand in groups ? |
| Answer» SOLUTION :ALONG the period , from LEFT to rightin the PERIODIC table, the electronegativity increases. On movingdown a GROUP, the electronegativity of the elements decreases. | |
| 5394. |
How does the pH affects the curdlling of milk ? |
| Answer» SOLUTION :Curds are obtained by coagulating milk by a process called curdling. The COAGULATION can be CAUSED by adding small quantity of old curd. The LACTOBACILLUS present in the curd acts on the lactose and converts it into lactic acid. The increased acidity causes the milk PROTEINS (casein) to coagulate and form curds. Hence acidic pH is required for curdling. Addition of any alkaline substance to milk will show down or not let it curdle. | |
| 5395. |
How does the metallic character change along the period? |
| Answer» Solution :As we go from left to right in a period, the metallic character decreases, because of the addition of anelectron in the same ENERGY shell each time. So, ATTRACTION between the NUCLEUS and the electrons in the outermost shell increases. Thus, tendency to lose an ELECTRON decreases and metallic characterdecreases. | |
| 5396. |
How does the metallic character of the elements vary (i) in a group, (ii) in a period of the modern periodic table ? |
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Answer» SOLUTION :(i) From top to bottom in GROUP - METALLIC character increases. (II) From LEFT to right in a period - metallic character decreases. |
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| 5398. |
How does the flow of acid rain water into a river make the survival of aquatic life in the river difficult ? |
| Answer» Solution :Acid rain water has pH LESS than 5.6 and when this water flows into river, it lowers its pH and HENCE makes the survival of AQUATIC life in river difficult. | |
| 5399. |
How does the electronic configuration of an atom relate to its position in the modern periodic table ? |
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Answer» Solution :In the periodic table, POSITION of an element depends on its ELECTRONIC CONFIGURATION. The position of an element can be determined by knowing the number of valence electron in its electronic configuration. For example, `""_(11)Na:underset(2)K""underset(8)L""underset(1)M:Na` possesses one electron in its valence SHELL. Hence, it BELONGS to group 1. The number of shells in the electronic configuration of an element determines its position in a period. For example, `""_(11)Na:underset(2)K""underset(8)L""underset(1)M:Na` has three shells(K, L and M). So, it belongs to 3rd period of the periodic table. |
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| 5400. |
How does the electronic configuration of an element relate to its position in the modern periodic table? |
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Answer» Solution :Electronic configuration DETERMINES the group number and period number and hence the exact position of an element in the modern periodic table. Period number: The number of electron shells gives period of an element. Group number: The number of valence electrons decides the group of an element. For elements with 1 or 2 valence electrons, their group number is same as the number of valence electrons. For elements with valence electrons > 2, group number = 10 + number of valence electrons. Examples: 1) Sodium has the atomic number 11. Its electronic configuration is (2, 8, 1). This means it has two electrons in K shell, 8 electrons in L shell, and I electron in M shell. SINCE it has three shells, its period is 3. Since it has valence electron, its group is 1. 2]) Carbon has the atomic number 6. Its electronic configuration is (2, 4). This means it has 2 electrons in K shell and 4 electrons in L shell. Since it has two shells, its period is 2. Since it has 4 valence electrons, its group is 4 + 10 = 14. |
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