InterviewSolution
Saved Bookmarks
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.
| 101. |
You are given the solution of lead nitrate. In ordedr to obtain a yellow precipitate you should mix with is solution of :A. potassium chlorideB. potassium nitrideC. potassium sulphideD. potassium iodide |
| Answer» Correct Answer - D | |
| 102. |
Which of the following are combination reactions? ` (i) 2KClO_(3)overset("Heat")to2KCl+3O_(2)` `(ii) MgO+H_(2)OtoMg(OH)_(2)` `(iii) 4Al+3O_(2)to 2Al_(2)O_(3)` `(iv) Zn+FeSO_(4)to ZnSO_(4)+Fe`A. `2KClO_(3) overset("Heat")to 2KCl + 3O_(2)`B. `MgO + H_(2)O to Mg(OH)_(2)`C. `4Al + 3O_(2) to 2Al_(2)O_(3)`D. `Zn + FeSO_(4) to ZnSO_(4) + Fe` |
|
Answer» Correct Answer - D Both the reactions (ii) and (iii) are the examples of combination reactions. |
|
| 103. |
Which of the following statements about the given reaction are correct? `3Fe(s)+4H_(2)O(g)rarrFe_(3)O_(4)(s)+4H_(2)(g)` 1. Iron metal is getting oxidised. 2.Water is getting reduced. 3.Water is acting as reducing agent. 4.Water is acting as oxidising agent.A. (i), (ii) and (iii)B. (iii) and (iv)C. (i), (ii) and (iv)D. (ii) and (iv) |
|
Answer» Correct Answer - C Statement (i), (ii) and (iv) are all correct. |
|
| 104. |
Classify the reactions into different type. `BaS_((aq))+ZnSO_(4(aq))to BaSO_(4(s))+ZnS_((aq))` |
| Answer» Double displacement reaction. | |
| 105. |
Explain the following in terms of gain or loss of oxygen with two examples each. (a) Oxidation (b) Reduction |
|
Answer» (a) Oxidation involves the gain of oxygen by a substance in a chemical reaction. For example, `2Zn(s) + O_(2)(g) overset("heat")to 2ZnO(s)` `2Ca(s) + O_(2)(g) overset("heat")to 2CaO(s)`. (b) Reduction involves the loss of oxygen from a substance in a chemical reaction. For example, `CuO(s) + H_(2)(g) overset("heat")to Cu(s) + H_(2)O (l)` `ZnO(s) + C(s) overset("heat")to Zn(s) + CO(g)` |
|
| 106. |
What do you mean by a precipitation reaction? Explain by giving examples. |
|
Answer» In a precipitation reaction, one of the products formed during the reaction does not dissolve in solution and gets settled at the surface of the container (beaker or tube). It is known as a precipitate. For example. `AgNO_(3) (aq) + NaCl (aq) to underset("(White ppt.)")(AgCl(s)) + NaNO_(3)(aq)` `BaCl_(2)(aq) + Na_(2)SO_(4)(aq) to underset("(White ppt.)")(BaSO_(4)(s)) + 2NaCl(aq)`. |
|
| 107. |
Classify the reactions into different type. `CuSO_(4(aq))+Pb_((s))to PbSO_(4(aq))+Cu_((s))` |
| Answer» Displacement reaction | |
| 108. |
(a) Give an example for a combination reaction which is exothermic. (b) Identify the oxidising agent and reducing agent in the following reaction. `H_(2)S + Cl_(2) to 2HCl + S` (c) Name the phenomenon due to which the taste and smell of oily food changes when kept for a long time in open. Suggest one method to prevent it. |
|
Answer» (a) `CaO + H_(2)O to Ca (OH)_(2) + "heat"`. (b) `H_(2)S + Cl_(2) to 2HCl + S` Oxidising agent `Cl_(2)` , Reducing agent `H_(2)S`. (c) It is known as rancidity. Only food must be kept in air tight containers. |
|
| 109. |
Identify the type of reaction from the following equations (i) `CH_(4) + 2O_(2) to CO_(2) + 2H_(2)O` (ii) `Pb(NO_(3))_(2) + 2KI to PbI_(2) + 2KNO_(3)` (iii) `CaO + H_(2)O to Ca(OH)_(2)` (iv) `CuSO_(4) + Zn to ZnSO_(4) + Cu`. |
|
Answer» (i) Combustion reaction `" "` (ii) Double displacement reaction (iii) Combination reaction `" "` (iv) Displacement reaction. |
|
| 110. |
Complete the missing components/variables given as x and y in the following reactions (a) `Pb(NO_(3))_(2) (aq) + 2KI(aq) to PbI_(2)(x) + 2KNO_(3)(y)` (b) `Cu(s) + 2AgNO_(3)(aq) to Cu(NO_(3))_(2)(aq) + x(s)` (c) `Zn(s) + H_(2)SO_(4)(aq) to ZnSO_(4)(x) + H_(2)(y)` (d) `CaCO_(3)(s) overset(x)to CaO(s) + CO_(2)(g)` |
| Answer» (a) x = yellow precipitate, y = (aq) (b) x = 2Ag(s) (c) x = (aq) , y = (g) (d) x = heat. | |
| 111. |
Which of the following gases can be used for storage of fresh sample of an oil for a long time?A. Carbon dioxide or oxygenB. Nitrogen or oxygenC. Carbon dioxide or heliumD. Helium or nitrogen. |
|
Answer» Correct Answer - D Both helium (He) and nitrogen `(N_(2))` can be used since these are chemically inert. In their presence, rancidity of fresh sample of an oil will not take place. |
|
| 112. |
Write balanced chemical equations for the following statements : (i) NaOH solution is heated with zinc granules (ii) Excess of carbon dioxide gas is passed through lime water (iii) Dilute sulphuric acid reacts with sodium carbonate (iv) Egg shells are dropped in hydrochloric acid (v) Copper (II) oxide reacts with dilute hydrochloric acid. |
|
Answer» (i) `Zn(s) + 2NaOH(aq) to Na_(2)ZnO_(2)(aq) + H_(2)(g)` (ii) `underset("(Lime water)")(Ca(OH)_(2)(aq)) + underset("(Exess)")(2CO_(2)(g)) overset("Excess")to Ca(HCO_(3))_(2)(aq)` (iii) `Na_(2)CO_(3)(s) + H_(2)SO_(4)(dil)to Na_(2)SO_(4)(aq) + CO_(2)(g) + H_(2)O(aq)` (iv) White coating of egg shell contains calcium carbonate. it reacts with hydrochloric acid. `CaCO_(3)(s) + 2HCl(aq) to CaCl_(2)(aq) + CO_(2)(g) + H_(2)O(aq)` `CuO(s) + 2HCl(dil) to CuCl_(2)(aq) + H_(2)O(aq)` |
|
| 113. |
Heating of sugar is called a `"_______"` reaction.A. Combination reactionB. Displacement reactionC. Double displacement reactionD. Decomposition reaction |
| Answer» Correct Answer - D | |
| 114. |
Antioxidants are used to prevent `"______"` of food containing fats and oils.A. ReductionB. OxidationC. Oxidation and reductionD. Decomposition |
| Answer» Correct Answer - B | |
| 115. |
In order to prevent the spoilage of potato chips, they are packed in plastic bags in an atmosphere of :A. `Cl_(2)`B. `H_(2)`C. `N_(2)`D. `O_(2)` |
| Answer» Correct Answer - C | |
| 116. |
All chemical reactions obey law of conservation of mass, hence, chemical equations should be `"_________".` |
| Answer» Correct Answer - balanced | |
| 117. |
The chemical reaction between quicklime and water is characterised by :A. evolution of hydrogen gasB. formation of slaked lime pracipitateC. change in temperature of mixtureD. change in comour of the product |
| Answer» Correct Answer - C | |
| 118. |
What are the factors which affect the rate of a chemical reaction. |
|
Answer» The rate of reaction depends upon the following factors. (i) Nature of the reactions: (i) `2NO_((g))+P_(2(g))to 2NO_(3(g))to "Fast"` `2CO_((g))+ O_(2(g))to 2CO_(2(g))to "Slow"` These reactions appear to be similar but the first is fast while second is slow. This is due to the difference in the amouts of energies which are required for breaking up of different bonds and different amounts of energies are released in the formation of different bonds. (b) ` 2Al +6HCl to 2AlCl_(3) + 3H_(2)uarr` `Zn +2HCl to NzCl_(2) +H_(2) uarr` Al and Zn react with dilute hydrochloric acid, `H_(2)` gas is liberated and water soluble salts of the metals are formed. however, the reaction of aluminium metal takes place faster as compared to zinc metla. The nature of metal is responsible fro this difference. Al is more reactive thn Zn. Therefore, the rate of reaction of Al with hydrochloric acid is higher than the of zinc. Nature of reactivity of reactants influences the rate of a chemical reaction. (ii) Concentration of the reactants: Greater the concentration of the reactants, faster is the reaction conversely, as the concentrations of the reactants decrease the rate of reaction also decrease. Dilute HCl reacts slowly with `CaCO_(3)` and thereby, `CaCO_(3)` disappears slowly and `CO_(2)` also liberates slowly on the other hand the reaction with concentrated HCl takes plce rapidly and `CaCO_(3)` disappears fast. Concentrated acid reacts faster than dilute acid, which means that rate of reaction is proporational to the concentration of reactants. Temperaturre: The rate of reaction increases with increase of temperature. In most of the cases, the rate of reaction becomes nearly double for 10K rise of temperature. In some cases, reactions do not take place at room temperature but take place at higher temperature. (iv) Presence of catalyst: A catalyst generally increases the speed of a reaction without itself being consumed in the reactin. In case of reverse reaction, a catalyst helps to attain the equilibrium quickly without disturibing the state of equilibrium. (v) Size of the particles of reactants : For a reaction involving a solid reactant or catalyst, smaller the particle size, greater is the surface area, and faster is the reaction. (vi) Presence of light : Some reactions do not take place in the dark but can take plce in the presence of light like photosynthesis or photochemical reactions. |
|
| 119. |
Name the law which requires the balancing of chemical equation. |
| Answer» The law is known as the law of Conservation of Mass. | |
| 120. |
Name the type of chemical reaction represented by the following equations : (a) `CaCO_(3)(s)overset("heat")to CaO (s) + CO_(2)(g)` (b) `CaO(s) + H_(2)O(l) overset("heat")to Ca(OH)_(2) (aq)` (c) `Zn(s) + H_(2)SO_(4)(aq) to ZnSO_(4) (aq) + H_(2)(g)` |
|
Answer» (a) Decomposition reaction (b) Combination reaction (c) Displacement reaction. |
|
| 121. |
The chemical reaction involved in the corrosion of iron metal is that of:A. oxidation as well as combinationB. reduction as well as combinationC. oxidation as well as displacementD. reduction as well displacement |
| Answer» Correct Answer - C | |
| 122. |
Why respriation is considered an exothermic reaction ? |
|
Answer» In the process of respiration glucose is broken into Carbon dioxide and energy is released. That is way, it is considered as an exothermic reaction. `C_(6) H_(12)O _(6(aq))+6O_(2(g))+6H_(2)O_((l))+`Energy (ATP) |
|
| 123. |
Name the factors on which the speed of a chemical reaction depends. |
| Answer» The speed of a chemical reaction depends on factors like size of the particles of reactants, concentration of the reactants, nature of the reactants, temperature of the reaction and presence of absence of catalyst. | |
| 124. |
To prevent rusting, a later of `underline("zinc")` metal is applied on iron sheets. |
| Answer» Explanation: Due to moisture and various components of atmosphere, oxidation of iron takes place. A certain type of raddish coloured solid layer collects on the iron surface. This layer is called rust. Its chemical formula is `Fe_(2)O_(3).xH_(2)O.` To avoid rusting, a layer of zinc metla is applied on iron sheets which prevents iron sheets from directly coming in contact with the atmosphere and hence, prevents rusting. This process of giving a thin coating of zinc on iron to protect it from rusting is called galvanisation. | |
| 125. |
You are given the following materials : `{:((i), "Iron nails",, (ii), "Copper sulphate solution"),((iii), "Barium chloride solution",, (iv), "Copper powder"),((v), "Ferrous sulphate crystals",, (vi), "Quick lime"):}` Identify the type of chemical reaction taking place when : (a) Barium chloride solution is mixed with copper sulphate solution and a white precipitate is observed. (b) On heating, copper powder in air in a china dish, the surface of copper powder becomes black. (c) On heating green ferrous sulphate crystals, reddish brown solid is left and a gas having smell of burning sulphur is noticed. (d) Iron nails when left dipped in blue copper sulphate solution becomes brownish in colour and blue colour of copper sulphate solution fades away. |
|
Answer» (a) The reaction is double displacement in nature. `{:(BaCl_(2)(aq) + CuSO_(4)(aq)to, BaSO_(4)(s) + CuCl_(2)(aq)),(,"(White ppt.)"):}` (b) It is an example of combination reaction. `{:(2Cu(s) + O_(2)(g) to, 2CuO(s)),(" ""(in air)", "Copper (II) oxide"),(," ""(Black)"):}` (c) The green crystals of ferrous sulphate have the chemical formula `FeSO_(4).7H_(2)O.` Upon heating, they lose molecules of water of crystallisation and it is an example of dehydration reaction. `underset("(Green)")(FeSO_(4)).7H_(2)Ooverset("heat")to FeSO_(4) + 7H_(2)O` Upon further heating, ferrous sulphate undergoes decomposition reaction as follows : `{:(2FeSO_(4)(s)overset("heat")to, Fe_(2)O_(3)(s) + SO_(2)(g) + SO_(3)(g)),(,"Ferric oxide(Reddish brown)"):}` Both the gases evolved have the small of burning sulphur. (d) This happens because of displacement reaction. Iron displaces copper from copper sulphate solution. Brownish coating of copper gets deposited on the iron nails. As the concentration of coppe sulphate in the solution decreases, the blue colour of the solution slowly fades. `{:(Fe(s) + CuSO_(4)(aq) to, FeSO_(4)(aq) + Cu(s)),(," ""(Brownish)"):}` |
|
| 126. |
(a) List two observations that are noticed when an iron nail is put inside copper sulphate solution. Write chemical equation for the reaction that occurs. (b) Explain two ways by which rancidity of food materials can be checked. |
|
Answer» (a) (i) Blue colour of copper sulphate solution changes to light green which is almost colourless. (ii) A brown mass gets deposited around the nail. (b) (i) Food materials must be kept in air tight bottles. (ii) In bags containing food materials such as potato chips and other food stuff, air must be replaced by nitrogen. |
|
| 127. |
(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. |
|
Answer» (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)"):}` |
|
| 128. |
Write a balanced chemical equation for each of the following reactions and also classify them. (a) Lead acetate solution is treated with dilute hydrochloric acid to form lead chloride and acetic acid solution. (b) A piece of sodium metal is added to absolute ethanol to form sodim ethoxide and hydrogen gas. (c) Iron (III) oxide on heating with carbon monoxide gas reacts to form solid iron and liberates carbon dioxide gas. (d) Hydrogen sulphide gas reacts with oxygen gas to form solid sulphur and liquid water. |
| Answer» `{:((a), Pb(CH_(3)COO)_(2)(s) + 2HCl(aq) to PbCl_(2)(s) + CH_(3)COOH (aq),, " Double displacement reaction"),((b), 2Na(s) + 2C_(2)H_(5)OH (l) to 2C_(2)H_(5)ONa(l) + H_(2)(g),, " Displacement reaction"),((c), Fe_(2)O_(3)(s) + 3CO(g) to 2Fe(s) + 3CO_(2)(g),, " Redox reaction"),((d), 2H_(2)S(g) + O_(2)(g) to 2S(s) + 2H_(2)O(l),, " Redox reaction".):}` | |
| 129. |
Why do we store silver chloride in dark coloured bottles? |
|
Answer» Silver chloride is a white solid. However, it is very senstive to sun light and decomposes in the presence of light to form silver (grey in colour) and chlorine. `2AgCl(s) overset("Sun light)")to underset("(Grey)")(2Ag(s)) + Cl_(2)(g)` In order to avoid action by sun light, it is kept in a coloured bottle. |
|
| 130. |
Identify the compound which is oxidised in the following reaction `H_(2)S + Br_(2) to 2HBr + S`. |
| Answer» `H_(2)S` is oxidised to S because `H_(2)S` Has lost hydrogen. | |
| 131. |
Write the essential condition for the following reaction to take place `2AgBr to 2Ag + Br_(2)` Write one application of this reaction. |
| Answer» This is an example of decomposition reaction and is also called photochemical reaction. It is carried in the presence of sunlight. | |
| 132. |
`"_________"` is a physical change.A. Ice changes into waterB. Milk is set into curdC. Ripening of fruitD. Respration process |
| Answer» Correct Answer - A | |
| 133. |
Write the balanced chemical equation for the following and identify the type of reaction in each case.A. Potassium bromide(aq) + Barium iodide(aq) `rarr` Potassium iodide(aq) + Barium bromide(s)B. Zinc carbonate(s) `rarr` Zinc oxide(s) + Carbon dioxide(g)C. Hydrogen(g) + Chlorine(g) `rarr` Hydrogen chloride(g)D. Magnesium(s) + Hydrochloric acid(aq) `rarr` Magnesium chloride(aq) + Hydrogen(g) |
|
Answer» (a) `2KBr (aq)+Bal_(2)(aq) rarr 2Kl (aq) + BaBr_(2)(s)` :Double displacement reaction (b) `ZnCO_(3)(s)rarr ZnO(s)+CO_(2)(g)` : Decomposition reaction (c) `H_(2)(g)+Cl(g) rarr 2HCl(g)` : Combination reaction (d) `Mg(s) +2HCl(aq) rarr MgCl_(2)(aq)+H_(2)(g)` : Displacement Reaction. |
|
| 134. |
`N_(2)+underline(square)to square NH_(3)` |
|
Answer» `N_2 +3H_2 to 2NH_3 ` It is a Combination reaction. |
|
| 135. |
Classify the reactions into different type. `AgNO_(3(aq))to AgCl_((s))+NaNO_(3(aq))` |
| Answer» (Double displacement reaction) Precipitation reaction | |
| 136. |
Classify the reactions into different type. `CaO_((s) +H_(2)O _((l))to Ca(OH)_(2(aq))+`Heat |
| Answer» Combination reaction [Exothermic reaction.] | |
| 137. |
`squareNaOH +H_(2)SO_(4)to "______"+squareH_(2)` |
|
Answer» `2NaOH + H_2SO_4 to Na_2SO_4 + 2H_2O` It is a Double displacement reaction . |
|
| 138. |
Identify the most reactive and least reactive metal : `Al, K, Ca, Au`. |
| Answer» Most reactive metal : K (potassium) , Least reactive metal : Au (gold). | |
| 139. |
`square Al + square HCl to square + square H_2` |
|
Answer» `2Al + 6HCl to 2AlCl_(3) + 3H_(2)` It is a Displacement reaction. |
|
| 140. |
`square overset(" sunlight") to squareAg+Cl_2` |
|
Answer» `2AgCl overset(" sunlight")to 2Ag + Cl_(2)` It is a Decomposition reaction. |
|
| 141. |
Classify the reactions into different type. `2H_(2) O_(2) underset("light")overset(UV)to 2H_(2)O+O_(2(l))` |
| Answer» Photolyticv decomposition is a chemical reaction in which molecules are broken down into smaller units through the absorption of light. | |
| 142. |
`squareKClO_(3) overset(Delta)to square + squareO_(2)` |
|
Answer» `2KClO_(3) overset(Delta)to 2KCl + 3O_(2)` It is Decomposition reaction. |
|
| 143. |
Catalyst |
|
Answer» (i) The substance in whose presence the rate of a chemical reaction changes, without causing any chemical change to it is called a catalyst. (ii) e.g. Potassium chlorate `(KClO_(3))` decomposes rapidly in presence of manganese dioxide `(MnO_(2))` to liberate `O_(2)` gas, where manganese dioxide acts as a catalyst. (iii) `2KClO_(3)overset(Delta)underset(MnO_(2))to2KCl +3O_(2)` |
|
| 144. |
Digestion of food is an example of decomposition reaction. |
| Answer» During digestion, the starch in the various food items gets decomposed into simple sugar while proteins get decomposed into amino acids. Hence digestion of food is an example of decomposition reaction. | |
| 145. |
How can the rate of the chemical reaction namely decomposition of hydrogen peroxide be increased ? |
|
Answer» (i) The chemical reaction in which two or more products are formed from a single reactant is called decomposition reaction. Hydrogen peroxide decomposes into water and oxygen. `{:(2H_(2)O_(2(l))to 2H_(2)O_((l))+O_(2)uarr),("Hydrogen" " ""Water" " ""Oxygen"),("peroxide"):}` (ii) The decomposition of hydrogen peroxide into water and oxygen takes place slowly at room temperature. However, the rate of this chemical reaction can be increased on adding manganese dioxide `(MnO_(2))` powder in it, here manganese dioxide acts as a catalyst. |
|
| 146. |
Give four uses of decomposition reaction. |
|
Answer» (i) Decomposition reaction helps all the living matter to return back to nature, after death. (ii) Management of garbage. (iii) Photosynthesis `to` decomposition of water. (iv) Photography `to` decomposition of silver bromide. (v) Used in chemical industry to obtain elements from complex compounds. (vi) Decomposition of agricultural waste leads to formation of compost. |
|
| 147. |
Give one example each of : (i) Thermal decomposition reaction (ii) Electrolytic decomposition reaction (iii) Photo decomposition reaction. |
|
Answer» (i) `CaCO_(3)(s) overset("Heat")to CaO(s) + CO_(2)(g)` (ii) `2H_(2)O(l) overset("Electric")to 2H_(2)(g) + O_(2)(g)` (iii) `2H_(2)O_(2)(l) overset("Light")to 2H_(2)O(l) + O_(2)(g).` |
|
| 148. |
What are neutralisation reactions ? Why are they so named ? Give one example. |
|
Answer» A neutralisation reaction is a chemical reaction between an acid and base dissolved in water. For example. `KOH(aq) + HNO_(3)(aq) to KNO_(3)(aq) + H_(2)O(aq)` It is called neutralisation as both `KNO_(3)` (salt) and `H_(2)O` that are formed as the products, are of neutral nature. |
|
| 149. |
In the reaction `SO_(2)+2H_(2)Srarr3S+2H_(2)O` the substance oxidised is |
|
Answer» (i) Here, `SO_(2)` is changing into S. This is the removal of oxygen from `SO_(2).` By definition, the removal of oxygen is called reduction. Thus, `SO_(2)` is being reduced to S. So, the substance being oxidised is hydrogen sulphide, `H_(2)S.` (ii) `H_(2)S` is changing into S. Thus is the removel of hydrogen from `H_(2)S.` By defination, the removal of hydrogen is known as oxidation. Thus, `H_(2)S` is being oxidised to S. So, the substance being oxidised is hydrogen sulphide, `H_(2)S.` |
|
| 150. |
Some examples of redox reaction are given. Identify the reductants and oxidants from them. `2H_(2) S+ SO_(2) to 3Sdarr +2H_(2)O` |
|
Answer» (i) In a redoxx reaction, the reductant transfers electrons to the oxidant. (ii) Then in the reaction, the reductant or reducing agent loses electrons and is oxidised and the oxidant or oxidizing agent gains electrons and is reduced. (iii) `therefore` Hence, in the above equation, reductant is `SO_(2)` and oxidant, is `H_(2)S` `MnO_(2)+4HCl to HnCl_(2) +2H_(2) O +Cl_(2)uarr` (i) Reductant: `MnO_(2)^(-)` as it loses oxygen. (ii) Oxidant: HCl - as it gains oxygen. |
|