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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.
| 5201. |
(i) Carbon cannot be used as reducing agent to obtain Mg from MgO. Why ? (ii) How is sodium obtained from molten sodium chloride ? Give equations of the reactions. (iii) How is copper obtained from its sulphide ore ? Give equations of the reactions. |
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Answer» Solution :(i) MG has more affinity for oxygen than CARBON. (II) Electrolytic reduction process of molten NaCl. At cathode : `2Na^(+) + 2e^(-) rarr 2Na` At anode : `2Cl^(-) rarr Cl_(2) + 2e` (III) `2Cu_(2)S + 3O_(2) rarr 2Cu_(2)O + 2SO_(2)` `2Cu_(2)O + Cu_(2)S rarr 6Cu + SO_(2)` |
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| 5203. |
(i) By the transfer of electrons, illustrate the formation of bond in magnesium chloride and identify the ions present in this compound. (ii) Ionic compounds are are solids. Give reasons. (iii) With the help of a labelled diagram show the experimental set up of action of steam on a metal. |
Answer» Solution :(i)  (II) Ionic COMPOUNDS are solids because of strong force of attraction between POSITIVE and negative IONS. (iii) EXPERIMENTAL set up is shown as under: 
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| 5204. |
(i) Bee sting leaves a chemical substances that causes pain and irrigation. Name the chemical substance. Identify the type of substance which may give relief on the sting area when applied on it. (ii) Mention the pH value below which tooth decay begins. How this fall below this value? Explain the ill effect of the acidic medium in the mouth. How can this be prevented? |
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Answer» Solution :(i) Methanoic ACID (HCOOH). USE of baking soda can give relief on the stung area when applied on it. (ii) TOOTH enamel, made of calcium PHOSPHATE does not dissolve in water. But it is corroded when pH is below 5.5 (ACIDIC). Bacteria present in the mouth produce acids by degradation of sugar and good particles remaining in the mouth. It can be prevented by using tooth paste, which is generally basic to neutralise excess acid. |
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| 5205. |
(i) Balance the following chemical equation MnO_(2)+HClrarrMnCl_(2)+Cl_(2)+H_(2)O (ii) What is decomposition reaction ? Explain it with suitable example. |
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Answer» Solution :`MnO_(2)+4HClrarrMnCL_(2)+2H_(2)O+Cl_(2)` (ii) A simple reactant breaks down to give simple PRODUCTS and the PROCESS is known as decompositionreaction Example : `CaCO_(3)(S) overset ("Heat")rarrunderset (("QUICK lime"))(CaO(S)+)CO_(2)(g)` |
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| 5206. |
(i) Atoms of same element with same atomic number but different mass number are called ……………. . (ii) Atoms of different elements with same number of neutrons are called ………….. . |
| Answer» SOLUTION :(i) ISOTOPES, (II) ISOTONES | |
| 5207. |
i] Atomic radius of hydrogen is 37 pm. Express it in metres. ii] How does atomic size vary in a group and in a period. |
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Answer» <P> Solution :`1 p m = 10^(-12) m`ATOMIC radius = `37 XX 10^(-12) m`. ii] In a group atomic size : increase down a group In a period atomic size: decrease in moving from left to right. |
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| 5208. |
(i) Atomic number of Mg and Al are 12 and 13, respectively. Write down their electronic configuration. (ii) Mention the period of the modern periodic table to which the above two elements belong. Give reason for your answer. |
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Answer» Solution :(i) MG : 2, 8, 2, Al: 2, 8, 3 (ii) `3^(rd)` PERIOD because electrons in these atoms are filled in K, L, M shells. |
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| 5209. |
(i) ……………….. Are the building blocks of matter. (ii) ……………is a triatomic molecule. |
| Answer» SOLUTION :(i) ATOMS and MOLECULES, (II) OZONE | |
| 5210. |
(i) An organic compound 'X' reacts with sodium metal to form sodium ethoxide and a gas 'Y'. Identify 'X' and 'Y'. (ii) What happens when ethanol is heated at 443 K with conc. H_(2)SO_(4)? |
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Answer» SOLUTION :(i) `2C_(2)H_(5)OH + 2Na+2C_(2)H_(5)ONa+H_(2)` .X. is ethanol and Y is HYDROGEN. (ii) `CH_(3)CH_(2)OHoverset(Conc.H_(2)SO_(4))underset"443K"rightarrowCH_(2)=CH_(2)H_(2)O` |
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| 5211. |
i] An element X has both K and L shells completely filled with electrons. The element has atomic number 10. Identify the element X. ii] In which group of the periodic table this element is placed? iii) Write its electronic configuration. What is its valency?. |
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Answer» Solution : i] the ELEMENT X is Neon (NE) ii] It is placed in the group 18 of the modern periodic table iii] ELECTRONIC CONFIGURATION of Neon is `{:(K,L),(2,8):}` Its valency is 0. |
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| 5212. |
(i) An element has electronic configuration 2, 8, 6. Explain its position in the periodic table. (ii) Size of sodium atom is bigger than that of hydrogen atom. Why? |
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Answer» Solution :(i) Third period and group 16. (II) SIZE INCREASES down the group as new shells are ADDED. |
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| 5213. |
(i) Acids as well as bases ionize in water . Name the ions produced by each in water. (ii) If we have hydrochloric acid and acetic acid of equal concentrationwhich will be a stronger acid and why? (iii) How will the concentration of hydrogen ions gets affected if an acid is diluted. |
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Answer» SOLUTION :(i) `H^+//H_3O^+` and `OH^(-)` respectively. (ii) Hydrochloric ACID will be a stronger acid, because it produces more `H^+` ions. (iii) Concentrationof `H^+` decreases with INCREASE in DILUTION. |
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| 5214. |
(i) Accountfor the following (a) White silverchloride turns grey in sunlight . (b) Brown coloured copper powder on heating in air turns into black coloured substance . (ii) What do you mean by : (a) Displacement rection (b) Reduction reaction Write balanced chemical equation . |
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Answer» Solution :(i) (a) Due to the decomposition of silver chloride into silver and chloride by SUNLIGHT . `2AgCl overset ("Sunlight")rarr2Ag+Cl_(2)` (b) Due to the oxidation of copper powder to copper oxide, BROWN COLOUR turns into BLACK `2Cu(S)+O(g)rarrCuO_(S)` (ii) (a) A chemical reaction in which the more reaction element displacement the less reactionelement its compounds is called displacement reaction . `CuSO_(4)(aq)+ZN(S)rarrZnSO_(4)(aq)+Cu(s)` (b) A chemical reaction in which hydrogen is added or oxygen is removed is called reductionreaction . `ZnO+CrarrZn+CO` |
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| 5215. |
(i) Account for the following : (a) White silver chloride turns grey in sunlight. (b) Brown coloured copper powder on heating in air turns into black coloured substance. (ii) What do you mean by (a) Displacement reaction (b) Reduction reaction (c) Combination reaction ? Write balanced chemical equation. |
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Answer» Solution :(i) (a) White coloured silver chloride undergoes DECOMPOSITION in the presence of sunlight and forms silver (GREY in colour) and chlorine. `{:(2AgCl(s) overset("Sun light")to 2Ag(s) + Cl_(2)(g)),("(White)" """ (Grey)"):}` (B) Brown coloured copper powder on HEATING in air GETS oxidised to copper oxide which is black in colour. `{:(2Cu(s) + O_(2)(g) overset("heat")to 2CuO(s)),("(Brown) " """ (Black)"):}` |
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| 5216. |
(i) A white powder is an active ingredient of antacids and is used for preparation of baking powder. Name the compounds and explain that how it is manufactured. Give chemical equation. (ii) Write a chemical equation to show the effect of heat on this compound. |
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Answer» Solution :(i) The compound is `NaHCO_3` (Sodium Hydrogen CARBONATE) (Commonly known as baking soda) Manufacturing of sodium hydrogen carbonate: `NH_3+NaCL+H_2O+CO_2 to NH_4Cl+NaHCO_3` (ii) On HEATING, Baking Soda DECOMPOSES into sodium carbonate, water and carbon dioxide. `2NaHCO_3 to^(DELTA) Na_2CO_3+H_2O+CO_2` |
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| 5217. |
(i) A non-metal X exists in two different forms Y and Z. Y is the hardest natural substance whereas Z is a good conductor of electricity. Identify X, Y, Z. (ii) A element, X, on reaction with oxygen forms an oxide XO_(2). The Oxide when dissolved in water turns blue litmus red. State whether element X is a metal or a non-metal. (ii) Name the metal which is alloyed with copper to make bronze. |
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Answer» Solution :(i) X - Carbon, Y - Diamond, Z - GRAPHITE (ii) NON - metal (iii) TIN |
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| 5218. |
(i) A local magician was showing magic in a village street. He took egg shell and poured a solution over it. As a result, effervescences were formed. When he took a burning matchstick over it, it went off. (a) Identify the solution poured and the substance present in eff shell. (b) What is the reason behind effervescences? ( c) Write its balanced chemical equation. (d) Give the common name of the substance present in the egg shell. (ii) Draw a labelled diagram to show that acid solution in water conducts electricity. |
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Answer» Solution :(i) (a) Solution is an acid. Substance in egg shell is calcium carbonate. (B) Effervescence is due to the EVOLUTION of `CO_2` gas. (C) `2HNO_3+CaCO_3 to 2Ca(NO_3)_2+H_2O+CO_2` (d) Lime stone. (II) 
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| 5219. |
(i) 2PbO+Crarr2Pb+CO_(2) (ii) MnO_(2)+4HClrarrMnCl_(2)+2H_(2)O+Cl_(2) What is redox reaction ? Identify the substance oxidised and the substance reduced in the above reaction. |
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Answer» Solution :Those REACTIONS in which both oxidation and reduction occur simultaneously . (i) PB O is REDUCED, C is oxidised. (ii) HCl is oxidised, `MnO_(2)` is reduced. |
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| 5220. |
{:("i. 22.4 litres","(a) Avogadro Number"),("ii. "6.023xx10^(23),"(b) Molar volume"),("iii. "2xx"vapour density","(c) 1 mole"),("iv. Mass/Atomic mass","(d) Molecular mass"):} |
| Answer» SOLUTION :`i-b,ii-a,iii-d,iv-c` | |
| 5221. |
{:("i. "_(17)Cl^(35)","_(17)Cl^(37),"(a) Isotones"),("ii. """_(6)Cl^(13)","""_(7)N&(14),"(b) Isobars"),("iii. "_(18)Ar^(40)","_(20)Ca^(40),"(c) "E=mc^(2)),("iv. Einstein's equation","(d) Isotopes"):} |
| Answer» SOLUTION :`i-d,ii-a,iii-b,iv-c` | |
| 5222. |
Hygroscopic substances do not change its physical state on exposure to air. |
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Answer» |
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| 5223. |
Hygroscopic substances are used as ………… |
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Answer» DRYING AGENTS |
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| 5225. |
Hygroscopic substances absorb moisture without changing their ...... |
| Answer» SOLUTION :PHYSICAL STATE | |
| 5226. |
Hydrogen sulphide gas reacts with oxygen to form soild _____ and _____ |
| Answer» SOLUTION :SULPHUR , WATER | |
| 5227. |
Hydrogen peroxide decomposes into water and oxygen. The uncatalysed reaction has activation energy of 86 KJ/mol . The E_(a) value in the presence of acetanilide is 112 KJ/mol and in the presence of MnO_(2) it is 49 KJ/mol. What conclusion can you draw from the above observations ? |
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Answer» Solution :(i) effect of ACTIVATION ENERGY on RATE (ii) comparing activation energy of the REACTION under different conditions (iii) effect of CHANGE in reaction conditions on the activation energy of the reaction. |
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| 5228. |
Hydrogen peroxide decomposes to water abd oxygen. The uncatalysed reaction has activation energy of 86 KJ/mol. The activation energy value in the presence of acetanilide is 112 KJ/mol and in the presence of MnO_(2) it is 49 KJ/mol . What conclusion can you draw from the above observations ? |
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Answer» Solution :The activation energy of a catalysed reaction in presence of `MnO_(2)` catalyst is 49 KJ/mol that is much less than the activation energy of an uncatalysed reaction that is 86 KJ/mol . This show that the rate of decomposition of `H_(2)O_(2)` is increased in the presence of `MnO_(2)` and hence it is a positive catalyst. THe activation energy of the catalysed reactionin the presence of acetanilide is 112 KJ/mol that is such greater THANTHAT of an uncatalysed reaction. This shows that the rate of decomposition of `H_(2)O_(2)` is decreased inthe presence of acetanilide and hence it is a negative catalyst. |
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| 5229. |
‘Hydrogen occupies a unique position in the Modern Periodic Table.' Justify the statement. |
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Answer» Solution :The position of hydrogen is unique in the Modern Periodic Table. This is because:i] The valence-shell configuration of hydrogen and alkali METALS is same - both have ONE electron. Thus, hydrogen has some PROPERTIES similar to alkali metals and hence, it must be placed in group I. ii] Both hydrogen and halogens require one electron to COMPLETE their valence configuration. So they show similarities in their properties and hydrogen can be placed in group 17. iii] Hydrogen also exhibits some properties different from both alkali metals and halogens. For instance, oxides of hydrogen (such as water) are neutral whereas alkalimetals form basic oxides and halogens form ACIDIC oxides. |
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| 5230. |
Hydrogen loses its electron to form H^(+), in this respect, it resembles |
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Answer» halogens |
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| 5231. |
Hydrogen is used to prepare vegatable ghee. |
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Answer» |
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| 5232. |
Hydrogen is not found free in the nature because hydrogen is a |
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Answer» reactive ELEMENT |
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| 5233. |
Hydrogen is not a metal but is has been assigned a place in the reactivity. Series of metals. Explain. |
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Answer» Solution :Though between is not a metal but eventhen it has been assigned a place in the ACTIVITY series. This reason is that like METALS, hydrogen also has a tendency to LOSE electron and forms a positive ion `H^+`. the metas which lose electrons less readily than hydrogen are PLACED below it and the metals which lose electrons more readily than hydrogen are placed above it in the reactivity series of metals. |
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| 5234. |
Hydrogen gas is passed through oil in order to |
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Answer» convert lower oil to higher oil |
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| 5235. |
Hydrogen gas is not liberated when a metal reacts with concentrated nitric acid because nitric acid |
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Answer» does not CONTAIN hydrogen atom |
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| 5236. |
Hydrogen : Fist period :: Lithium : __________ |
| Answer» Solution :SECOND period - The first period contains HYDROGEN(1) and Helium (2) Lithium.s ATOMIC number is 3,THEREFORE, it i s put in the second period. | |
| 5238. |
Hydrogen chloride is formed when sodium chloride is treated with |
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Answer» conc. `HNO_(3)` |
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| 5239. |
Hydrogenchlorideis a______ molecule. |
| Answer» SOLUTION :heterodiatomic | |
| 5241. |
Hydrogen bond is nothing but strong dipole-dipole attraction. Justify. |
| Answer» SOLUTION :When a covalent bond is formed between atoms of different elements, partial charges are developed on the bonded atoms. This molecule is called DIPOLE. Due to the presence of opposite partial charges on the atoms, dipole-dipole atttractions exist between the molecules. In case of polar covalent bond between hydrogen and highly electronegative atom, the magnitude of partial charges will be much GREATER. As a result, the dipole-dipole ATTRACTIONS becme stronger and this is called hydrogen bond. | |
| 5242. |
Hydrogen being a highly inflammable gas oxygen being a supporter of combustion, yet water up of hydrogen and oxygen is used to extinguish fire why ? |
| Answer» Solution :It is because of the PROPERTY of water as compound. It is not INFLAMMABLE, but the constituent elements of water hydrogen and OXYGEN have DIFFERENT PROPERTIES. | |
| 5243. |
Hydrogen and oxygen gases are produced at the cathode and anode respectively in the electrolysis of acidulated water. What is the ratio of the volumes of hydrogen and oxygen gases ? |
| Answer» SOLUTION :HYDROGEN and oxygen gases are PRODUCED in the ratio of `2:1`. | |
| 5245. |
Hydrochloric acid, nitric acid and sulphuric acid are known as mineral acids because they |
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Answer» attack MINERALS |
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| 5246. |
Hydrochloric acid is a stronger acid than acetic acid. This is because |
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Answer» HYDROCHLORIC acid does not ionize. |
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| 5247. |
_____hydrocarbons undergo addition reactions. |
| Answer» SOLUTION :UNSATURATED | |
| 5249. |
How would you test that a given gas is carbon dioxide ? |
| Answer» Solution :CARBON DIOXIDE GAS will TURN limewater milky. | |
| 5250. |
How would you show that silver is chemically less reactive than copper? |
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Answer» Solution :By displacement REACTIVE silver can be SHOWN to be chemically less reactive than copper or copper is more reactive than silver. If a piece of silver is immersed in a solution of copper sulphate. No reactive will TAKE place because silver is less reactive than copper and will not DISPLACE copper from the copper sulphate solution. `CuSO_4(aq)+Ag(s) to No reaction` On the other HAND if a copper plate in a solution of silver nitrate, copper will slowly displace silver from the solution and blue solution of copper nitrate is formed. `2AgNO_3(aq)_(Colourl ess)+Cu(s)toCu(NO_3)2_(Blue)+2Ag(s)` This shows that copper is more reactive than silver. |
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