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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.
| 51. |
When acids and alkalis react together, `"_______"` and `"______"` is formed. |
| Answer» Correct Answer - slat, water | |
| 52. |
Digestion of food is a chemical change. |
| Answer» Correct Answer - True | |
| 53. |
The gases hydrogen and chlorine donot react with each other even if kept together for a long time. However, in the presence of sun light, they readily combine. What does actually happen ? |
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Answer» We know that in chemical reactions, energy is needed to break the bonds present in the reacting molecules so that they may combine to form the products. In the present case, sun light is the source of energy in the form of photons. The energy made available helps in breaking the bonds present in the reactant molecules and the chemical reaction leading to hydrogen chloride gas takes place. `H_(2)(g) + Cl_(2)(g) overset("sunlight")to 2HCl(g)` |
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| 54. |
The life on earth is protected from ultraviolet radiation of the sun. |
| Answer» Correct Answer - Ozone layer | |
| 55. |
Formation of Itric axide from nitrogen and oxygen is a `"______"`reaction. |
| Answer» Correct Answer - combination | |
| 56. |
Write the reaction of formation of `Fe ^(2+)` by the reduction `Fe^(3+)` by making use of the symbol (e) ? |
| Answer» `Fe _((aq))^(3+)+e^(-)underset("Reduce")toFe _((aq))^(2+)` | |
| 57. |
How many products are formed in each of the above reaction ? |
| Answer» In all the above reactions, only one product is formed. | |
| 58. |
What is the number of molecules of reactants taking part in the above reactions ? |
| Answer» `{:(NH_(3), +, HCL, to, NH_(4) Cl), ("1 molecule",,"1molecule",,),(2Mg,+, O_(2) , to, 2MgO),("2 molecules ",, "1 molecule",,),(CaO,+, H_(2)O ,to, Ca(OH)_(2) +"Heat"),("1 molecule",, "1molecule",,):}` | |
| 59. |
A state prior to the formation og the `O_(2)` molecule. |
| Answer» Nascent oxygen. | |
| 60. |
It takes time for pieces of Shahabad tiles to disappear in HCl, but its powder disappears rapidly. |
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Answer» (i) When HCl is added to Shahabad stone effervescence of `CO_(2)` is formed. (ii) The `CO_(2)` effervescence is formed slowly with the pieces of Shahabad tiles while at the faster speed with the powder. (iii) This is because the rate of a reaction depends upon the size of the particles of the reactants taking part in the reaction. (iv) Smaller the size of the reactant particles more is the surface area available for the reaction and higher is the rate of reaction. (v) Hence, it takes time for pieces of Shahabad tiles to disappear in HCl, but its powder disappears rapidly. |
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| 61. |
Which of the following is a combination and which is a displacement reaction? (a) `Cl_(2)+2KIto2KCl+I_(2)` (b) `2K+Cl_(2)to2KCl` |
| Answer» (a) It is displacement reaction. (b) It is a combination reaction. | |
| 62. |
The diagram displays a chemical reaction. Obserbve carefully and answer the question. Mention one commerical use of this salt. |
| Answer» Silver chlorides is used in photography. | |
| 63. |
The diagram displays a chemical reaction. Obserbve carefully and answer the question. Write the chemical equation of the reaction that takes place. |
| Answer» `2AgCl_((s))overset("sunlight")to 2Ag_((s))+Cl_(2(g))` | |
| 64. |
The diagram displays a chemical reaction. Obserbve carefully and answer the question. Identify the type of chemical reaction that will take plce and define it. How will the colour of the salt change ? |
| Answer» Photochemical decomposition reaction: Those reaction in which a compound breaks down into simple substances in the presence of light are called Photochemical decomposition reactions. The colour of salt will change from white to grey. | |
| 65. |
A small amount of ferrous sulphate was heated in a hard glass test tube : (i) Write the equation involved in the above reaction. (ii) What type of reaction is taking place ? |
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Answer» (i) `2FeSO_(4)(s) overset("heat")to Fe_(2)O_(3)(s) + SO_(2)(g) + SO_(3)(g)` (ii) It is a thermal decomposition reaction. |
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| 66. |
Why are eatables preferably packed in aluminium foils ? |
| Answer» Aluminium oxide `(Al_(2)O_(3))` is formed on the surface of metal. It stops any further reaction of the metal with air (oxygen) and water. The eatables donot get spoiled. | |
| 67. |
How will you know whether a sample of cheese has become rancid or not ? |
| Answer» If the cheese starts giving foul smell, it means that it has become rancid. | |
| 68. |
Which of the following can be decompose by the action of light?A. NaClB. KClC. AgClD. CuCl |
| Answer» Correct Answer - C | |
| 69. |
The process of respiration is:A. an oxidation reaction which is endothermicB. a reduction reaction which is exothermicC. a combination reaction which is endothermicD. an oxidation reacton which is exothermic |
| Answer» Correct Answer - D | |
| 70. |
A white precipitate will be formed if we add common salt solution to :A. `Ba(NO_(3))_(2)` solutionB. `KNO_(3)` solutionC. `AgNO_(3)` solutionD. `Mg(NO_(3))_(2)` solution |
| Answer» Correct Answer - C | |
| 71. |
Susting of iron is an oxidation reaction. |
| Answer» Correct Answer - True | |
| 72. |
Ammonium chloride is a sublimable salt. |
| Answer» Correct Answer - True | |
| 73. |
Reaction that releases energy is called Enodothermic. |
| Answer» False. Reaction that releases energy is called Exothermic. | |
| 74. |
Observe the following picture write down the chemical reaction with expanation. |
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Answer» In the above diagram, process of rusting takes place. (ii) A certain type of raddish coloured solid layer collects on the metallic surface. (iii) This layer is called rust. (iv) Its chemical formula is `Fe_(2)O_(3). xH_(2)O.` The rust is formed by an electrochemical reaction. (v) Different regions on the surface of iron become anode and cathode. (vi) Fe is oxidised to `Fe ^(2+)` in hte anode region . `Fe_((s))to Fe_((aq))^(2+)+2e^(-)` (vii) `O_(2)` reduces to form water in the cathofe region. `O_(2(g))+4H_((aq))^(+) +4e^(-) to 2H_(2)O_((l))` When `Fe^(2+)` ions migrate from the anode region, they react with water and further get oxidised to from `Fe^(3+)` ions. (viii) A reddish coloured hydrate oxide is formed from `Fe^(3+)` ions, it is called rust. It collects on teh surface. (ix) `2F_((aq))^(3+) +4H_(2)O_((l))to Fe_(2) O_(3). H_(2)O_((s)) +6H_((aq))^(+).` (x) Due to various components of atmosphere, oxidation of matals takes place, concequently resulting in their damage. (xi) This is called Corrosion Iron rusts and a raddish coloured layer is collected on it. This is corrosion of iron. |
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| 75. |
Acatalyst slows down the rate of reaction to make a better product. |
| Answer» False. Catalyst speed up the rate of reaction. | |
| 76. |
The reaction in which oxygen is added to the substance is called `"_____"` reaction |
| Answer» Correct Answer - oxidation | |
| 77. |
The removal of oxygen from a substance is called :A. oxidationB. corrosionC. reductionD. rancidity |
| Answer» Correct Answer - C | |
| 78. |
What is the difference between the following two reactions ? (a) `Mg + 2HCl to MgCl_(2) + H_(2)` (b) `NaOH + HCl to NaCl + H_(2)O`. |
| Answer» (a) It is a single displacement reaction. (b) It is a double displacement reaction also called neutralisation reaction. | |
| 79. |
A checal reaction involves ` "________"`A. Only breaking of bonds.B. Only formation of bonds.C. Both breaking and formation of bonds.D. None of these. |
| Answer» Correct Answer - C | |
| 80. |
What is rust ? |
| Answer» It is a brown mass known as hydrated ferric oxide. Its formula is `Fe_(2)O_(3).xH_(2)O`. | |
| 81. |
What is rust?A. Sodium oxideB. Iron oxideC. Copper oxideD. Silver oxide |
| Answer» Correct Answer - B | |
| 82. |
Which of the following is formed when Sodium hydroxide reacts with hydrochloric acid ? `A. Calcium ChlorideB. Hydrogen ChlorideC. Sodium hydroxideD. Sodium Chloride |
| Answer» Correct Answer - D | |
| 83. |
Because of the formation of which of the following, lime water turns milky when carbon dioxide is passed through it?A. Calcium CarbonateB. Calcium bicarbonateC. Calcium hydroxideD. Sodium Carbonate |
| Answer» Correct Answer - A | |
| 84. |
When carbon dioxide is passed through lime water it turns milky. Why ? |
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Answer» Lime water (Calcium hydroxide) combines with carbon dioxde to form a suspension of calcium carbonate when turns lime water milky. `Ca(OH)_(2(aq))+CO_(2(g))toCaCO_(2(s))+H_(2)O_((l))` |
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| 85. |
Combustion is the rapid reaction between carbon dioxide and fuel. |
| Answer» False. Combustion is the rapid reaction between oxygen and fuel. | |
| 86. |
If the number of atoms of each element is not some on the two sides of an equation |
| Answer» Unbalanced equation | |
| 87. |
A precipitate is an insoluble solid formed from solution during a chemical reaction. |
| Answer» Correct Answer - True | |
| 88. |
Write a balanced chemical equation with state symbols for the following reaction: Heated iron metal reacts with steam to from iron (II, III) oxide, `(Fe_(3)O_(4))` and hydrogen. |
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Answer» This reaction can be written in the form of a word equation as: `"Iron"+"Steam"to "Iron"(II,III)"oxide"+"Hydrogen"` Now, Symbol of iron is fe `"Formula of steam is" H_(2)O" "("It is the same as water")` `"Formula or iron (II,III) oxide is" Fe_(3)O_(4)" "(Given)` And, Formula of hydrogen is `H_(2)` By writing the symbols and formulae of all the substances in the above word equation, we get the following skeletal chemical equation: `" "Fe+H_(2)OtoFe_(3)O_(4)+H_(2)` Here Fe and `H_(2)O` are reactants whereas `Fe_(3)O_(4)and H_(2)` are the products. Let us count the number of atoms of various types in the reactants and products : `{:(,"In reactants","In products"),("No . of Fe atoms:",1,3),("No . of H atoms:",2,2),("No . of O atoms:",1,4):}` We can see that the number of iron atoms on the left side of the equation is only 1 but there are 3 iron atoms on the right side. Now, to have 3 iron atoms on the left side, we multiply Fe by 3 and write it as 3Fe. Thus, `" "3Fe+H_(2)Oto Fe_(3)O_(4)+H_(2)` Let count the number of various types of atoms on both the sides again : `{:(,"In reactants","In products"),("No . of Fe atoms:",3,3),("No . of H atoms:",2,2),("No . of O atoms:",1,4):}` Now the number of iron atoms is equal on both side (3 each) and the number of hydrogen atoms also equal (2 each). But the number of oxygen atoms is not equal. There is only 1 oxygen atom on the left side but 4 oxygen atoms on the right side. So, to have 4 oxygen atoms on the left side, we multiply `H_(2)O` by 4 and write it as `4H_(2).` This will give us : `" "3Fe + 4H_(2)Oto Fe_(3)O_(4)+H_(2)` Let us count the number of various atoms on the two sides once again: `{:(,"In reactants","In products"),("No . of Fe atoms:",3,3),("No . of H atoms:",8,2),("No . of O atoms:",1,4):}` The number of hydrogen atoms now becomes unequal. There are 8 hydrogen atoms on the left side but only 2 hydrogen atoms on the right side. Now, to gel 8 hydrogen atoms on the right side, we multiply `H_(2)` by 4 and write it as `4H_(2).` This given us the following equation : `" "3Fe+4H_(2)OtoFe_(3)O_(4)+4H_(2)`Let us count the number of various types of atoms on both the sides of this equation: `{:(,"In reactants","In products"),("No . of Fe atoms:",3,3),("No . of H atoms:",8,8),("No . of O atoms:",4,4):}` The above chemical equation contains an equal contains an equal number of Fe, H and O atoms in the reactants and Iron (Fe) si a solid, steam `(H_(2)O)` is a gas, iron (II,III) oxide `(Fe_(3)O_(4))` is a solid and hydrogen `(H_(2))` is a gas. So, we can write the above chemical equation with state symbols as follows: `" "3Fe(s)+ 4H_(2)O(g)to Fe_(3)O_(4)(s)+4H_(2)(g)` |
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| 89. |
Iron sulphide reacts with sulphureic acid. |
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Answer» Iron sulphide reacts with sulphureic acid to from ferrous sulphate and hydrogen sulphide. `underset("Iron sulphate")(FeS_((s))) + underset("Sulphuric acid")(H_(2)SO_(4(aq))) to underset("Ferrous sulphate ")(Fe SO_(4(aq)))+ underset("Hydrogen sulphide")(H_(2)S_((g)))uarr` |
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| 90. |
write the balanced chemical equations for the following reaction. (a) Sodium carbonate on reaction with hydrochloric acid in equal molar concentrations gives sodium chloride and sodium hydrogen carbonate. (b) Sodium hydrogen carbonate on reaction with hydrochloric acid gives sodim chloride, water and liberates carbon dioxide. (c) Copper sulphate on tretment with potassium iodide precipitates cuprous iodide iodide `(Cu_(2)I_(2))`, liberates iodine gas and also forms potassium sulphate. |
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Answer» (a) `Na_(2)CO_(3) (s) + HCl (aq) to NaCl(aq) + NaCl(aq) + NaHCO_(3) (aq)` (b) `NaHCO_(3) (s) + HCl (aq) to NaCl(aq) + H_(2)O (aq) + CO_(2)(g)` (c) `2CuSO_(4) (s) + 4KI (aq) to Cu_(2)I_(2) (s) + 2K_(2)SO_(4) (aq) + I_(2) (g)` |
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| 91. |
Glucose reacts with oxygen. |
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Answer» When glucose combines with oxygen, carbon dioxide and water are formed with the release of energy. `underset("Glucose")(C_(6)H_(12)O_(6))+ underset("Oxygen")(6O_(2(g)))to underset("Carbon dioxide")(6CO_(2(g))) + underset("Water")(6H_(2)O_((l))) +"energy"` |
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| 92. |
Sulphur dioxide and hydrogen sulphide reacts. |
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Answer» Sulphur dioxide and hydrogen sulphide react to form sulphur and water. `underset("Sulphur dioxide")(SO_(2(g)))+ underset("Hydrogen sulphide")(2H_(2)S_((g)))to underset("Sulphur")(3Sdarr) + underset("Water")(2H_(2)O_((l)))` |
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| 93. |
Sodium carbonate solution is added to calcium chloride solution. |
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Answer» When sodium carbonate solution is added to calcium chloride solution, solid calcium carbonate and aqueous solution of sodium chloride is formed. It is a double displacement reaction. `underset("Sodium carbonate")(Na_(2) CO_(3(aq)))+ underset(" Calcium chlorde")(CaCL_(2(aq)))to underset(" Calcium carbonate")(CaCO_(3(s)))+ underset("Sodium chloride")(2NaCl_((aq)))` |
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| 94. |
Copper reacts with concentrated Nitric acid. |
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Answer» When copper reacts with concentrated nitric acid, reddish coloured poisonous nitrogen dioxide gas is formed. `underset("Copper")(Cu_((s)))+ underset("conc. Natric acid")(4HNO_(3(aq)))to underset("Copper nitrate")(Cu (NO_(3))_(2(aq)))+ underset ("Nitrogen dioxide ")(2nO_(2(g)))+ underset("Water")(2H_(2)O_((l)))` |
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| 95. |
Why is potassium permangante used for cleaning of water tanks ? |
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Answer» (i) Potassium permanganate oxidises dissolved iron, manganese and hydrogen sulphide into solid particles. (ii) `KMnO_(4)` is used to remove organic matter from the water tank by oxidation which also removes unwanted taste and odour. (iii) It also kills harmful bacteria and fungi. |
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| 96. |
Which is the oxidant used ro purification of drinking water? |
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Answer» (i) Chlorine is a strong oxidant commonly used in water treatment for oxidation and disinfection. (ii) Even Potassium permaganate can be used as oxidant for purification of water. |
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| 97. |
Which among the following is (are) double displacement reaction (s)? (i) `Pb+CuCl_(2)rarrPbCl_(2)+Cu` (ii) `Na_(2)SO_(4)+BaCl_(2)rarrBaSO_(4)+2NaCl` (iii) `C+O_(2)rarrCO_(2)` (iv) `CH_(4)+2O_(2)rarrCO_(2)+2H_(2)O`A. (i) and (iv)B. (ii) onlyC. (i) and (ii)D. (iii) and (iv) |
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Answer» Correct Answer - B Only reaction (ii) is double displacement in nature. |
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| 98. |
What type of reaction is this: `Nh_(2) SO _(4)+ BaCl_(2)to BaSO_(4) +2NaCl.` |
| Answer» It is a double displacement reaction. | |
| 99. |
Grapes hanging on the plant do not ferment but after being plucked from the plant can be fermented. Under what conditions do these grapes ferment? Is it a chemical or a physical change? |
| Answer» Grapes hanging on the plants are living in nature. Their immune system does not allow any fermentation. However, when these are plucked, they are no longer living. They undergo fermentation under aerobic conditions (in the absence of air or oxygen). The other factors which favour fermentation are enzyme and temerature between `25^(@) C` to `30^(@) C`. The fermentation is a chemical change. | |
| 100. |
A White salt upon heating decomposes to give brown fumes and a residue is left behind. (i) Name the salt. (ii) Write the equation for the decomposition reaction. |
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Answer» (i) The salt is lead nitrate with formula `Pb(NO_(3))_(2)` (ii) `2Pb(NO_(3))_(2)(s) overset("heat")to 2PbO(s) + underset("(Brown fumes)")(4NO_(2)(g)) + O_(2) (g)` |
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