Important Assertion reasoning type questions from physical and inorganic chemistry

 

SOLUTIONS 

(a)  Both assertion and reason are correct statements, and reason is the correct explanation of the assertion. 

(b)  Both assertion and reason are correct statements, but reason is not the correct explanation of the assertion. 

(c)  Assertion is correct, but reason is wrong statement. 

(d)  Assertion is wrong, but reason is correct statement. 

(e) both are incorrect 

 1.) Assertion: Molarity of a solution in liquid state changes with temperature. 

      Reason: The volume of a solution changes with change in temperature.  

  Ans: (a)  

 2.) Assertion: If a liquid solute more volatile than the solvent is added to the solvent, the vapour pressure of the solution may increase i.e., ps > po. 

   Reason: In the presence of a more volatile liquid solute, only the solute will form the vapours and solvent will not. 

    Ans: (c) 

3.) Assertion: If one component of a solution obeys Raoult’s law over a certain range of composition, the other component will not obey Henry’s law in that range. 

      Reason: Raoult’s law is a special case of Henry’s law 

Ans: (b) 

4.) Assertion: When methyl alcohol is added to water, boiling point of water increases.  

      Reason: When a volatile solute is added to a volatile solvent elevation in boiling point is observed. 

 Ans: (d) 

 5.) Assertion: When NaCl is added to water a depression in freezing point is observed.  

        Reason: The lowering of vapour pressure of a solution causes depression in the freezing point  

Ans: (a)  

6.  Assertion: Molality is a better method to express concentration than molarity 

     Reason: Molality is defined in terms of mass of solvent and not mass of solution. 

     Ans- a 

7.   Assertion: Soda bottles are sealed under high pressure. 

     Reason: High pressure increases the solubility of carbon dioxide gas. 

    Ans- a 
 8.   Assertion: There will not be any change in concentration of an ethanol and water   mixture containing 85% ethanol by volume on boiling. 

   Reason: It is because azeotropes boil out in constant composition. 

    Ans- d 

9.   Assertion: Benzene and hexane form an ideal solution. 

 Reason: Both benzene and hexane are hydrocarbons. 

 Ans- c      

10.    Assertion: 1 molar NaCl solution has higher boiling point than one molar urea. 

        Reason: NaCl dissociates into ions in solution. 

       Ans- a 

11.      Assertion: A raw mango placed in concentrated salt solution loses water shrivel into pickle. 

     Reason: The salt solution is hypotonic compared to the raw mango. 

     Ans- c

12.     Assertion: Helium is mixed with nitrogen and oxygen in diving cylinders 

   Reason: Helium has comparatively low KH(Henry constant) value. 

  Ans- c 

13.      Assertion: Ice containing dissolved sugar will melt at a higher temperature than pure ice. 

    Reason: Dissolving sugar in water leads to a depression in freezing point. 

   Ans-d 

14.  Assertion: Molar mass of acetic acid in benzene calculated using colligative property is almost 

double the actual value. 

 Reason: Acetic acid dimerises in solution. 

Ans- a                                

15.  Assertion: Vapour pressure of a solution is more that of the pure solvent. 

        Reason: The solute particles occupy certain area of the surface of the solution which reduces the amount of vapour.  

Ans- d 

  

 ELECTROCHEMISTRY 

1.  Assertion: It is possible to make a cell with a pair of same type of half cells. 

Reason: Change in concentration varies the electrode potential. 

Ans- a 

2.  Assertion: When aqueous sodium chloride solution is electrolysed, Oxygen gas is produced at the anode. 

Reason: It is due to the overpotential for oxidation of water to oxygen. 

Ans- a 

3.  Assertion: Molar conductivity of an electrolyte increases with decrease in concentration. 

Reason: The mobility of ions decrease with increase in concentration. 

Ans- a 

4.  Assertion: The electrode potential of standard hydrogen electrode is zero. 

Reason: There is no potential difference at the electrode – solution interface in this case. 

Ans-c 

5.  Assertion: Reduction of 1 mole of Cu2+ ions require 2 faraday of charge.. 

Reason: 1 Faraday is equal to the charge of 1 mole of electrons 

Ans- a 

6.  Assertion: Fuel cells are pollution free. 

Reason: Fuel cells use hydrogen like fuels along with oxygen gas for current production. 

Ans- b 

7.  Assertion: Lechlanche cell gives constant voltage throughout its life. 

Reason: The overall reaction of button cell does not involve any ion in solution whose concentration can change during its life time. 

Ans- d 

 8.  Assertion: Coating iron with zinc prevents rusting. 

Reason: The coating of zinc prevents moist air to come in contact with the metal. 

Ans-c 

9.  Assertion: More negative the electrode potential greater is the power to act as oxidising agent. 

 Reason: As the electrode potential becomes more negative there is greater tendency to undergo oxidation 

Ans-d 

10.  Assertion: Secondary cells are cells which can be recharged after use. 

 Reason: The products are electrolysed back to the initial reactants during recharge of the cell. 

 Ans- a 

CHEMICAL KINETICS 

1.  Assertion: Hydrolysis of methyl ethanoate is a pseudo first order reaction. 

 Reason: Water is present in large excess and therefore its concentration remained constant throughout the reaction. 

Ans- a 

2.  Assertion: Order of a reaction can be zero. 

Reason: In the case of heterogeneous catalysis, the reaction becomes independent of concentration at high concentration of the reaction. 

Ans- a 

3.  Assertion: The slowest elementary step in a complex reaction decides the rate of the reaction. 

  Reason: The slowest elementary step always has the smallest molecularity. 

Ans- c 

4.  Assertion: A catalyst increases the rate of a reaction. 

 Reason: The catalyst increases the activation energy which in turn increases the rate of the reaction. 

Ans- c 

5.  Assertion: Activation complex for the forward reaction will have lower energy than that for the backward reaction in an exothermic reaction. 

    Reason: Reactants have greater energy than products for an exothermic reaction. 

Ans- d 

6.  Assertion: Increase in temperature increases rate of reaction. 

Reason: More colliding molecules will have energy greater than threshold energy. 

Ans- a 

7.  Assertion: Unit of rate constant is independent of order of reaction. 

Reason: The power of concentration terms in the rate equation keep changing with change in order. 

Ans- d 

8.  Assertion: Increase in concentration of reactant will not change the rate for a zero order reaction. . 

  Reason: Rate constant for a zero order reaction is a constant for a particular initial concentration. 

Ans-   b            

 9.  Assertion: The half life of a reaction is independent of initial concentration for a first order reaction. 

  Reason: The integrated rate law for a first order reaction is independent of initial concentration. 

Ans- c 

10.  Assertion: Half life of a reaction can be used to predict order of a reaction. 

Reason: The relationship between half life and initial concentration of the reactant is dependant on order. 

Ans-  a 

  

           SURFACE CHEMISTRY 

  

1.  Assertion: Colloids are heterogeneous mixture. 

Reason: The particle size of the dispersed phase is too large for it to form a homogeneous mixture 

Ans- a 

2.  Assertion: Adsorption is a surface phenomenon. 

Reason: The intermolecular forces at the surface of the adsorbent is unequal in different directions. 

Ans- b 

3.  Assertion: A beam of light passed through the colloidal solution will illuminate the path traced by it in the colloid. 

Reason: Colloids have particle size in between that of solution and suspension. 

Ans- b 

4.  Assertion: Associated colloids form micelles only below a particular concentration called the critical micelle concentration. 

Reason: At low concentration they behave as crystalloids. 

Ans- d 

5.  Assertion. Barbers rub the face with alum stones after giving a shave. 

 Reason: Alum stones have antiseptic properties. 

Ans-c 

6.  Assertion: When two oppositely charged colloids are mixed together, they coagulate mutually. 

      Reason: The charge of the two colloids gets neutralized destabilizing the colloid. 

Ans- a 

7.  Assertion: Brownian movement is partially responsible for the stability of the colloid. 

Reason: The phenomenon increases the entropy of the system enhancing the stability. 

Ans-a 

8.  Assertion: Shape selective catalysis is possible for zeolitic catalyst. 

Reason: Zeolites are sodium aluminosilicates with definite crystal structure. 

Ans- b 

9.  Assertion: Enzymes are highly selective in their functions. 

 Reason: The enzymes catalysis involves a lock and key mechanism. 

Ans-a 

10.  Assertion: Keeping an electric field during dialysis enhances the process. 

Reason: The dialysis process involves removing old solvent for new pure solvent. 

Ans- b  

  

GENERAL PRINCIPLES OF EXTRACTION  

(in this current year, it is deleted Part)  

  

1.  Assertion: NaCN is used during the concentration of a mixture of PbS and ZnS. 

    Reason: ZnS forms a cyano complex which is soluble and hence wetted by water. 

2.  Assertion: Limestone is added to blast furnace during extraction of iron. 

    Reason: Limestone decomposes to calcium oxide and carbon dioxide. 

3.  Assertion: Hydrometallurgy is in metallurgical process of copper. 

    Reason: Hydrogen is a good reducing agent. 

4.  Assertion: The extracted copper obtained is called blister copper. 

    Reason: The carbon dioxide gas formed tries to escape leading to the formation of blisters. 

5.  Assertion. Nickel can be refined by complexing with CO 

Reason: Nickel carbonyl complex is volatile and easily decomposable.. 

6.  Assertion: Sulphide ores are calcined before reduction. 

 Reason: The sulphide ore gets converted to oxide which is easier to reduce. 

7.     Assertion: The anodes in Hall Heroult process have to be replaced periodically. 

     Reason: The metal anode reacts with oxygen formed and gets converted to oxide 

 8.     Assertion: Pine oil is added to the powdered ore and water during froth floatation. 

 Reason: Pine oil enhances the non-wettability of the ore particles in water. 

9.  Assertion: Sodium cyanide is used for leaching of bauxite. 

Reason: Golds and Silver forms soluble complex with Cyanide ion. 

10.  Assertion: Anode mud is useful in making the refining of copper economical. 

Reason: Anode mud contains rare metals like gold, silver, selenium etc. 

  

            p-BLOCK ELEMENTS 

  

1.  Assertion: Oxygen has less negative electron gain enthalpy than sulphur. 

Reason: Oxygen is more electronegative than sulphur. 

Ans-b 

2.  Assertion: Sulphur has greater tendency for catenation than oxygen 

Reason: O – O bond is weaker than S – S bond. 

Ans- a 

3.  Assertion: H2O is a liquid while H2S is a gas 

Reason: There is stronger intermolecular hydrogen bonding in H2S. 

Ans-c 

4.  Assertion: Both the S – O bonds in sulphur dioxide are equal. 

       Reason: Sulphur dioxide molecule exhibits resonance. 

Ans- a 

5.     Assertion. Ozone is a powerful oxidising agent. 

Reason: Ozone easily decomposes to oxygen. 

Ans-b 

6.  Assertion: SF6 is a very inert molecule. 

Reason: It is difficult to break the S – F bonds. 

Ans-c 

7.  Assertion:  H2Se is more acidic than H2Te 

Reason: Bond enthalpy decrease with increased in size of the atom.. 

Ans-d 

8.  Assertion: Sulphuric acid is highly corrosive. 

Reason: Sulphuric acid is a powerful oxidising agent. 

Ans-b 

9.     Assertion: Sulphur dioxide is a good bleaching agent. 

Reason: Sulphur dioxide readily oxidises to sulphate in solution. 

Ans-a 

10.  Assertion: Ka1 for sulphuric acid is very high compared to Ka2. 

Reason: Sulphuric acid is a dibasic acid which forms two series of salts. 

Ans- b 

11.  Assertion: Halogens have characteristic colour. 

Reason: Halogens readily accepts electrons to form halide ion. 

Ans-b 

12.  Assertion: Fluorine shows only positive oxidation state. 

Reason: Fluorine has an exceptionally small size. 

Ans-c 

13.  Assertion: Chlorine water is a more permanent bleaching agent than sulphur dioxide. 

Reason: Chlorine water oxidises while sulphur dioxide reduces. 

Ans- a 

14.  Assertion: Fluorine forms only one oxo acid HOF. 

Reason: Fluorine does not have d-orbitals in its valence shell. 

Ans- a 

15.  Assertion: Inter-halogen compounds are better oxidising agents than halogens 

Reason: X – X’ bonds are stronger than X – X bonds. 

Ans-a 

16.  Assertion: Noble gases have very low boiling point. 

     Reason: Noble gases have a fully filled valence shell configuration. 

Ans-b 

17.     Assertion: Among the noble gases only Xenon forms large number of compounds 

Reason: Xenon has an ionisation enthalpy which is similar to that of Oxygen atom. 

Ans-c 

18.  Assertion: Hydrochloric acid is more acidic than hydrobromic acid 

Reason: The H – X bond becomes weaker for HBr compared to HCl. 

Ans-b 

19.  Assertion: Sulphuric acid can be used to prepare hydrochloric acid from chloride salts. 

Reason: Sulphuric acid is less volatile than hydrochloric acid. 

Ans-c 

20.  Assertion: Ka1 for sulphuric acid is very high compared to Ka2. 

Reason: Sulphuric acid is a dibasic acid which forms two series of salts. 

  

Ans-b 

                    d and f-BLOCK ELEMENTS   

  

1.  Assertion: Transition metals have high enthalpy of atomisation. 

    Reason: d-block elements have strong metallic bonds 

Ans-a 

2.     Assertion: Manganese has an exceptionally low melting point in 3d series. 

Reason: Manganese has weak metallic bonds due to electronic repulsion. 

Ans-c 

3.  Assertion: Scandium does not show variable oxidation state. 

Reason: Scandium has only one electron in the 3d orbital. 

Ans-b 

4.  Assertion: Fe2+ readily oxidizes to Fe3+ in solution. 

Reason: Fe3+ has a stable d5 configuration. 

Ans- a 

5.  Assertion. Among the 3d series only copper shows +1 oxidation state. 

Reason: Cu+ ion has high negative hydration enthalpy in solution compared to Cu. 

Ans-b 

6.  Assertion: Cobalt (II) readily oxidises to Co (III) while forming complexes. 

Reason: Co(III) has a stable t2g3 configuration in complexes. 

Ans-c 

7.  Assertion: Transition metals show very low degree of para magnetism. 

Reason: Transition metal atoms have large number of unpaired electrons. 

Ans-d 

8.  Assertion: Transition metals are very good catalysts. 

Reason: Transition metals are strong metals with high melting points. 

Ans-b 

9.  Assertion: Transition metals readily forms alloys. 

Reason: Transition metals can be melted easily and mixed together. 

Ans-b 

10.     Assertion: Potassium permanganate is a good oxidising agent in acidic medium. 

           Reason: Permanganate readily reduces to manganese dioxide in acidic medium. 

   Ans- c 

 11.     Assertion: Sodium dichromate cannot be used as a primary standard in titrations. 

       Reason: Sodium dichromate is hygroscopic in nature. 

Ans- a 

12.  Assertion: Orange solution of dichromate turns yellow when pH of the solution is increased. 

Reason: The colour of dichromate gets bleached when alkali is added. 

Ans-c 

13.  Assertion: Lanthanide contraction is more than actinoid contraction. 

        Reason: Actinoids have 5f orbitals being filled which are more dispersed in space compare to 4f orbitals. 

Ans-d 

14.  Assertion: Misch metal is a pyrophoric alloy. 

Reason: Misch metal is prepared from lanthanoids. 

Ans-b 

15.  Assertion: Actinoids show more variety in oxidation state than lanthanoids. 

Reason: Actinoids have comparatively larger sixe than lanthanoids. 

Ans-b 

16.  Assertion: Zirconium and Hafnium have similar properties. 

       Reason: Zirconium and Hafnium lie in the same group of the periodic table. 

Ans-b 

17.  Assertion: Highest oxidation states of d-block metals are usually seen in oxides and oxoanions. 

Reason: Oxygen is capable of forming pπ – dπ bonds with transition metals. 

Ans-a 

18.  Assertion: Higher oxidation states in transition metals are more covalent than lower oxidation states. 

Reason: Higher oxidation states involve more d-electrons than lower oxidation states. 

Ans-a 

19.  Assertion: Manganate ion is paramagnetic while permanganate ion is diamagnetic. 

      Reason: Manganate ion has two unpaired electrons. 

Ans- c 

20.     Assertion: HCl cannot used for acidification in permanganometric titrations. 

Reason: HCl gets oxidised to chlorine in the presence of permanganate. 

Ans- a 

  COORDINATION COMPOUNDS 

 1.  Assertion: EDTA is used to treat lead poisoning. 

Reason: EDTA forms very stable complexes with lead. 

Ans- a 

2.  Assertion: Coloured complexes become colourless once the ligands are removed. 

Reason: The d – d transitions are not possible since d orbitals become degenerate. 

Ans-a 

3.  Assertion: Carbon monoxide forms low spin complexes with metals. 

Reason: Carbon monoxide is neutral oxide. 

Ans-b 

4.  Assertion: Carbon monoxide is a deadly poison. 

Reason: CO can form strong complexes with haemoglobin. 

Ans-a 

5.  Assertion. Tetrahedral complexes cannot exhibit geometrical isomerism. 

Reason: Tetrahedral complexes are chiral in nature. . 

Ans-c 

6.  Assertion: An octahedral complex with two bidentate ligands is always optically active. 

Reason: The cis – isomer of the octahedral complex is chiral. 

Ans-d 

7.  Assertion: Ionisation isomerism is shown by complexes having ambidentate ligands. 

    Reason: Ambidentate ligands have two possible ligating centres. 

Ans- d 

8.     Assertion: The colour of a complex change when one ligand is replaced by another. 

Reason: The magnitude of d-orbital splitting is decided by the nature of the ligand.  

Ans-d 

9.     Assertion: [Fe (CN)6]3- is more paramagnetic than [FeF6]3-. 

  Reason: [FeF6]3- has a greater number of unpaired electrons. 

Ans- (D) 

10.  Assertion: [Co(NH3)6]3+ is an inner orbital complex.     

Reason: [Co(NH3)6]3+ forms an octahedral complex. 

Ans- B 

 
 

     Answer coming soon