94420 + Interview Questions in Chemistry in Class 12

1.	Lead salts react with K_2CrO_4 to give precipitates of :
Answer» WHITE COLOUR yellow colour RED colour blue colour SOLUTION :`PbCl_2 + K_2CrO_4 to underset("Lead chromate (Yellow Colour)")(PbCrO_4) + 2KCl`

Discussion

2.	Lead sulfide has fcc structure. The edge length of the unit cell of PbS crystal is 500 pm What is its density ?
Answer» Solution :MOLECULAR mass of PBS = 207.2+32 = 239.2 Edge length, a = 500 , pm NUMBER of molecules per unit cell, Z=4 (for fcc structure) Density of unit cell, `d= (Zxx M)/(N_A XX a^3 xx 10^(-30)) g cm^(-3)` `therefore d = (4xx239.2 g "mol"^(-1))/(6.022 xx 10^(23) "mol"^(-1) xx (500)^3 xx 10^(-30) cm^3)` `= (956.8)/(75.275) g cm^(-3) = 12.7 g cm^(-3)`

Discussion

3.	Lead sugar is :
Answer» `PbCl_2` `PB(NO_3)_2` `PbSO_4` `(CH_3COO)_2Pb` ANSWER :D

Discussion

4.	Lead poisoning in the body can be removed by:
Answer» EDTA in the FORM of clacium dihydrogen SALT cis-platin Zeisse's salt DMG Answer :C

Discussion

5.	Lead pipes can be used for:
Answer» SOFT water HARD water Both hard and soft water None of the above Answer :B

Discussion

6.	Lead pencils contains :
Answer» LEAD nitrate Pb Graphite Mixture of lead and carbon. Answer :C

Discussion

7.	Lead pipes are readily corroded by :
Answer» `H_2SO_4` HCL `CH_3COOH` PURE water Answer :C

Discussion

8.	Lead pipes are not suitable for drinking water, because :
Answer» LEAD forms basic lead carbonate Lead reacts with water CONTAINING air to form `Pb(OH)_2` A layer of lead DIOXIDE is deposited over pipes Lead reacts with air OT form litharge Answer :B

Discussion

9.	Lead pencil contains:
Answer» Pb FeS Graphite PbS Answer :C

Discussion

10.	Lead pencil' contains
Answer» PBS Graphite FeS Pb ANSWER :B

Discussion

11.	Lead (P) causes
Answer» RADIOACTIVE pollution Air pollution Soil pollution All of the above Answer :B

Discussion

12.	Lead pencil is manufactured by mixing clay with :
Answer» Lead Graphite Lamp black Bone black Answer :B

Discussion

13.	Lead nitrate of heating gives lead oxide, nitrogen dioxide and oxygen. This reaction is known as
Answer» COMBUSTION Combination Displacement Decompostion Solution :`2Pb(NO_(3))_(2)overset("heat")to 4NO_(2)+2PbO +O_(2)` It is decomposition REATION because lead nitrite on heating DECOMPOSES to Lead oxide, nitrogen dioxide and oxygen.

Discussion

14.	Lead nitrate on heating gives lead oxide, nitrogen dioxide and oxygen. The reaction is known as:
Answer» Combustion Combination Displacement Decomposition Answer :D

Discussion

15.	Lead (IV) oxide is obtained by
Answer» heating LEAD (II) oxide STRONGLY in air heating lead strongly in pure OXYGEN oxidising lead with CONC. `HNO_(3)` none of these Solution :`Pb_(3)O_(4)+4HNO_(3) overset(Delta)to2Pb(NO_(3))_(2)+2H_(2)O+PbO_(2)`

Discussion

16.	Lead is present in petrol in the from of _________as_________agent.
Answer» ANSWER :A::B::C::D

Discussion

17.	Lead is only slightly attacked dilute hydrochloric acid , because
Answer» Pb is less ELECTROPOSITIVE than HYDROGEN `PbO_2` film is always present on Pb, which RESISTS chemical ATTACK PBO film is formed , which resists chemical attack by acid a protective coating of `PbCl_2` is formed on the Pb surface Answer :D

Discussion

18.	Lead is not affected by dilute HCl in cold, because:
Answer» PB is less electronegative than H PbO FILM is formed which resists chemical attack by acid A protective coating of `PbCI_2` is formed on Pb SURFACE `PbO_2` film is ALWAYS present on Pb surface, which resists chemical attack Answer :C

Discussion

19.	Lead in water can cause.
Answer» EYE disease Arthritis Kidney damage Hair falling Answer :C

Discussion

20.	Lead has been placed in qualitative group analysis Ist and 2nd because
Answer» It shown the valency one and two it FORMS insoluble `PbCI_(2)` It form LEAD salphide `PbCI_(2)` is parially soluble in water SOLUTION :Pb form `PbCI_(2)` in GROUP I and PbS in group II Lead salt are partiallysoluble in water

Discussion

21.	Lead has been placed in the group I and II because
Answer» it shows the valency of one and two it forms INSOLUBLE `PbCl_(2)` it forms lead sulphide it is partially soluble in water Solution :`PbCl_(2)` is partially soluble in water and dissolves completely only in hot water. So , part of it goes to group II, Where it is precipitated as PbS.

Discussion

22.	Lead exhausted in the atmosphere by automobiles using leaded petrol (i.e.,tetraethyl lead for improving octant number ) is a lethal air pollutant, which causes :
Answer» PARALYSIS of MUSCLES and LOSS of appetite Nervous depression Gastritis and diarrhoea All of the above Answer :D

Discussion

23.	Lead containers are generally used for storing radioactive materials. This is because :
Answer» LEAD is stable lead has high ATOMIC mass lead is a poor conductor lead is a GOOD ABSORBER. Answer :D

Discussion

24.	Lead accumulator cell consists of
Answer» `20% H_(2)SO_(4)` solution `3.2 M H_(2)SO_(4)` solution `H_(2)SO_(4)` of sp. GRAVITY 1.15 dilute solution of `H_(2)SO_(4)` ANSWER :B

Discussion

25.	Lead accumulator is a secondary storage cell because
Answer» it is an irreversible cell electrical ENERGY is previouslystored in it from an EXTERNAL source electrolysis occurs in it it involves `H_(2)SO_(4)` solution Solution :After SETTING the cell, it should be charged.

Discussion

26.	Lead accumulator cell can be maintained in good working condition when
Answer» the CELL is allowed to run upto 1.7 V the cell is not allowed to run upto 1.17 V the cell is not completely removed from the cell the cell is not disconnected when not in use Solution :Voltage decreases with decrease in specific GRAVITY of `H_(2)So_(4)`.

Discussion

27.	Lead accumulator.
Answer» SOLUTION :

Discussion

28.	Leaching process is used to get :-
Answer» Ag Au Both None Answer :C

Discussion

29.	Leaching of gold is carried out by.....
Answer» `CaCN_2` `KCN` `HCN` `NACN` ANSWER :B

Discussion

30.	Leaching of an ore is done by
Answer» HALL's process Serpeck's process Cyanide process Hall-Heroult process Answer :C

Discussion

31.	Leaching is commercially carried out for in the concentration of :
Answer» Galena Argentite Copper pyrites Tin stone Solution :Leaching is carried out for the concentration of argentire `(Ag_(2)S)` (i) `Ag_(2)S+4NaCN overset("AIR")to 2Na[Ag(CN)_(2)]^(-)+Na_(2)S overset("Air")to Na_(2)SO_(4)+S`

Discussion

32.	Leaching is also called as……..
Answer» HAND picking Electrolysis Chemical process Magnetic SEPARATION process Answer :C

Discussion

33.	Leaching .
Answer» Solution :It is a (CHEMICAL) process used in the concentration of an ore by EXTRACTING soluble maerial from an insoluble solid by dissolving in a suitable solvent. This method is used in the concentration process of ores of AL, Ag, AU, etc.

Discussion

34.	Leaching is a process of concentration of ores. Explain the leaching ofalumina from bauxite.
Answer» ANSWER :REFER to the answer of MARCH 2010 (C )

Discussion

35.	Leaching is a process of:
Answer» Reduction Concentration Reformation Oxidation Answer :B

Discussion

36.	Le-Chatelier's principle is not applicable to which of the following reaction?
Answer» `N_2(g)+3H_2(g) ltimplies 2NH_3(g)` `PCL_5(g) ltimplies PCL _3(g)+CL_2(g)` `FE(s) +S(s) ltimplies FES(s) ` `CACO _3(s)ltimplies CAO (s) +CO_2` Answer :C

Discussion

37.	Le-Chatelier's principle is applicable only to a
Answer» SYSTEM in equlibrium Irreversible REACTION Homogeneous reaction HETEROGENOUS reaction ANSWER :A

Discussion

38.	Le chatelier's principle If a system at equilibrium is subjected to a change of any one of the factors such as concentration, pressure or temperature, the system adjusts itself in such a way so as to minimise the effect of that change. Change of pressure: If a system in equilibrium consists of gases, then the concentrations of all the components can be altered by changing the pressure.When the pressure on the system is increased, the volume decreases proportionately.The total number of moles per unit volume will now be more and the equilibrium will shift in the direction in which there is decrease in number of moles i.e., towards the direction in which there is decrease in volume. Effect of pressure on melting point : There are two types of solids : (a)Solids whose volume decreases on melting e.g. ice, diamond , carborundum, magnesium nitride and quartz. Solid (higher volume)hArr Liquid (lower volume) The process of melting is facilitated at high pressure, thus melting point is lowered. (b)Solids whose volume increase on melting, e.g. Fe,Cu, Ag,Au, etc. Solid (lower volume)hArr Liquid (higher volume) In this case the process of melting becomes difficult at high pressure, then melting point becomes high. (c )Solubility of subtances : When solid substance are dissolved in water, either heat is evolved (exothermic) or heat is absorbed (endothermic). KCl+aq hArr KCl(aq)-heat In such cases,solubility increase with increase in temperature. Consider the case of KOH, when this is dissolved heat is evolved. KOH+aq hArr KOH(aq)+heat In such cases, solubility decrease with increase in temperature. (d)Solubility of gases in liquids : When a gas dissolves in liquid, there is decreases in volume. Thus, increases of pressure will favour the dissolution of gas in liquid. Effect of temperature: Le-Chatelier's principle predicts a system at equilibrium will tend to shift in the endothermic direction when temperature is raised, for then energy is absorbed as heat and the rise in temperature is opposed.Conversely, an equilibrium will shift in the exothermic direction if the temperature is lowered, for then energy is released and the reduction in temperture is opposed Van't Hoff equation shows the dependence of equilibrium constant K on temperaure as : d/(dT)lnK=(DeltaH^@)/(RT^2) or ln K="constant"-(DeltaH^@)/R.1/T The plot of log K against 1/T is a straight line with positive slope ( K being the equilibrium constant of a reaction ), which of the following is then correct ?
Answer» The reaction is endothermic in nature The reaction WILLL be exothermic in nature The reaction goes to farther extent on raising the temperature None of these Solution :Since the slope of the STRAIGHT LINE graph between LOG K and `1/T` is positive ,`DeltaH_("reaction")` would be negative, i.e., the forward reaction would be exothermic.

Discussion

39.	Le chatelier's principle If a system at equilibrium is subjected to a change of any one of the factors such as concentration, pressure or temperature, the system adjusts itself in such a way so as to minimise the effect of that change. Change of pressure: If a system in equilibrium consists of gases, then the concentrations of all the components can be altered by changing the pressure.When the pressure on the system is increased, the volume decreases proportionately.The total number of moles per unit volume will now be more and the equilibrium will shift in the direction in which there is decrease in number of moles i.e., towards the direction in which there is decrease in volume. Effect of pressure on melting point : There are two types of solids : (a)Solids whose volume decreases on melting e.g. ice, diamond , carborundum, magnesium nitride and quartz. Solid (higher volume)hArr Liquid (lower volume) The process of melting is facilitated at high pressure, thus melting point is lowered. (b)Solids whose volume increase on melting, e.g. Fe,Cu, Ag,Au, etc. Solid (lower volume)hArr Liquid (higher volume) In this case the process of melting becomes difficult at high pressure, then melting point becomes high. (c )Solubility of subtances : When solid substance are dissolved in water, either heat is evolved (exothermic) or heat is absorbed (endothermic). KCl+aq hArr KCl(aq)-heat In such cases,solubility increase with increase in temperature. Consider the case of KOH, when this is dissolved heat is evolved. KOH+aq hArr KOH(aq)+heat In such cases, solubility decrease with increase in temperature. (d)Solubility of gases in liquids : When a gas dissolves in liquid, there is decreases in volume. Thus, increases of pressure will favour the dissolution of gas in liquid. Effect of temperature: Le-Chatelier's principle predicts a system at equilibrium will tend to shift in the endothermic direction when temperature is raised, for then energy is absorbed as heat and the rise in temperature is opposed.Conversely, an equilibrium will shift in the exothermic direction if the temperature is lowered, for then energy is released and the reduction in temperture is opposed Van't Hoff equation shows the dependence of equilibrium constant K on temperaure as : d/(dT)lnK=(DeltaH^@)/(RT^2) or ln K="constant"-(DeltaH^@)/R.1/T For the reaction 1/2N_2(g)+1/2O_2(g)hArrNO(g)
Answer» Total PRESSURE at EQUILIBRIUM will CHANGE Concentration of all the component at equilibrium will not change Concentration of all the component at equilibrium will remain same Equilibrium will shift in the forward direction Solution :NA

Discussion

40.	Le chatelier's principle is
Answer» if a system in equilibrium is subjected to a change of concentration, pressure of TEMPERATURE , the equilibrium SHIFTS in the direction that tends to a null the effect of change. APPLICABLE to all of dynamic equilibrium given to study the effect to state variables none of the above Answer :A::B::C

Discussion

41.	Le-Chatelier's principle is
Answer» if a system in equilibrium is SUBJECTED to a CHANGE of concentration, pressure or temperature, the equilibrium shifts in the direction that tends to undo the effect of change applicable to all TYPE of dynamic equilibrium applicable to IRREVERSIBLE system applicable to all physical and chemical equilibrium SOLUTION :Let-Chatelier.s principle is applilcable for reversible system.

Discussion

42.	Le chatelier's principle If a system at equilibrium is subjected to a change of any one of the factors such as concentration, pressure or temperature, the system adjusts itself in such a way so as to minimise the effect of that change. Change of pressure: If a system in equilibrium consists of gases, then the concentrations of all the components can be altered by changing the pressure.When the pressure on the system is increased, the volume decreases proportionately.The total number of moles per unit volume will now be more and the equilibrium will shift in the direction in which there is decrease in number of moles i.e., towards the direction in which there is decrease in volume. Effect of pressure on melting point : There are two types of solids : (a)Solids whose volume decreases on melting e.g. ice, diamond , carborundum, magnesium nitride and quartz. Solid (higher volume)hArr Liquid (lower volume) The process of melting is facilitated at high pressure, thus melting point is lowered. (b)Solids whose volume increase on melting, e.g. Fe,Cu, Ag,Au, etc. Solid (lower volume)hArr Liquid (higher volume) In this case the process of melting becomes difficult at high pressure, then melting point becomes high. (c )Solubility of subtances : When solid substance are dissolved in water, either heat is evolved (exothermic) or heat is absorbed (endothermic). KCl+aq hArr KCl(aq)-heat In such cases,solubility increase with increase in temperature. Consider the case of KOH, when this is dissolved heat is evolved. KOH+aq hArr KOH(aq)+heat In such cases, solubility decrease with increase in temperature. (d)Solubility of gases in liquids : When a gas dissolves in liquid, there is decreases in volume. Thus, increases of pressure will favour the dissolution of gas in liquid. Effect of temperature: Le-Chatelier's principle predicts a system at equilibrium will tend to shift in the endothermic direction when temperature is raised, for then energy is absorbed as heat and the rise in temperature is opposed.Conversely, an equilibrium will shift in the exothermic direction if the temperature is lowered, for then energy is released and the reduction in temperture is opposed Van't Hoff equation shows the dependence of equilibrium constant K on temperaure as : d/(dT)lnK=(DeltaH^@)/(RT^2) or ln K="constant"-(DeltaH^@)/R.1/T Au(s)hArrAu(l)
Answer» HIGH PRESSURE, low temperature High pressure, high temperature Low pressure, high temperature Low pressure, low temperature Solution :Since density of GOLD decreases after melting THEREFORE it is favourable at low pressure and high temperature

Discussion

43.	Le-Chatelier principle is not applicable to
Answer» `H_(2(g))+I_(2(g))hArr2HI_((g))` `Fe_((s))+S_((s))+hArrFeS_((s))` `N_(2(g))+3H_(2(g))hArr2NH_(3(g))` `N_(2(g))+O_(2)hArr2NO_(2(g))` Solution :LE chatelier PRINCIPLE is not applicable to solid-solid equlibrium.

Discussion

44.	Le-blanc process is employed in the manufacturing of
Answer» BAKING SODA CAUSTIC soda Soda ASH and potash Plaster of Paris Answer :C

Discussion

45.	LDPE is a homopolymer, while nylon 6, 6 is a copolymer. Explain
Answer» Solution :Polymer formed by the polymerisation of one type of monomer is known as homopolymer. LDPE 9 or LDP) is formed by the polymerisation of ETHENE `(CH_2=CH_2)`. So it is a homopolymer. Polymer formed by the polymerisation of two or more different monomers is called copolymer. Since nylon 6,6 is formed by the polymerisation of ADIPIC acid and HEXAMETHYLENE DIAMINE, it is a copolymer.

Discussion

46.	ldentify the monohydrie unsaturated alcohol.
Answer» `CH_3-CH_2OH` `CH_2=CHOH` `{:(CH_2OH),(\|),(CH_2OH):}` `C_6H_5CH_2OH` SOLUTION :`CH_2=CHOH`

Discussion

47.	ldentify the incorrect statement(s)?
Answer» <P>The ratio of the OBSERVED molar volume to ideal molar volume is called compressibility factor The value of VAN der Waals' constants 'a' and 'b' is independent of the nature of gas. At high temperature and low pressure, the behaviour of any gas. can be explained by `P+(an^(2))/(V^(2))(V-nb)=nRT` `H_(2) and He` gases are difficult to liquefy because their Boyle temperature is less than `0^(@)C` Answer :B::C

Discussion

48.	Layers of carbon atoms in graphite are held together by :
Answer» 1. Covalent bonds 2. Hydrogen bonds 3. VAN der Waals forces 4. Double bonds Answer :C

Discussion

49.	Law of raciprocd proportions can be used to determine :
Answer» ATOMIC WEIGHT of gas equivalent WEIGHTS molecular weights of gases None of these Answer :B

Discussion

50.	Law of multiple proportion was given by
Answer» Lavosivier Dalton Proust Gaylussac Answer :B

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

Lead salts react with K_2CrO_4 to give precipitates of :

Lead sulfide has fcc structure. The edge length of the unit cell of PbS crystal is 500 pm What is its density ?

Lead sugar is :

Lead poisoning in the body can be removed by:

Lead pipes can be used for:

Lead pencils contains :

Lead pipes are readily corroded by :

Lead pipes are not suitable for drinking water, because :

Lead pencil contains:

Lead pencil' contains

Lead (P) causes

Lead pencil is manufactured by mixing clay with :

Lead nitrate of heating gives lead oxide, nitrogen dioxide and oxygen. This reaction is known as

Lead nitrate on heating gives lead oxide, nitrogen dioxide and oxygen. The reaction is known as:

Lead (IV) oxide is obtained by

Lead is present in petrol in the from of _________as_________agent.

Lead is only slightly attacked dilute hydrochloric acid , because

Lead is not affected by dilute HCl in cold, because:

Lead in water can cause.

Lead has been placed in qualitative group analysis Ist and 2nd because

Lead has been placed in the group I and II because

Lead exhausted in the atmosphere by automobiles using leaded petrol (i.e.,tetraethyl lead for improving octant number ) is a lethal air pollutant, which causes :

Lead containers are generally used for storing radioactive materials. This is because :

Lead accumulator cell consists of

Lead accumulator is a secondary storage cell because

Lead accumulator cell can be maintained in good working condition when

Lead accumulator.

Leaching process is used to get :-

Leaching of gold is carried out by.....

Leaching of an ore is done by

Leaching is commercially carried out for in the concentration of :

Leaching is also called as……..

Leaching .

Leaching is a process of concentration of ores. Explain the leaching ofalumina from bauxite.

Leaching is a process of:

Le-Chatelier's principle is not applicable to which of the following reaction?

Le-Chatelier's principle is applicable only to a

Le chatelier's principle is

Le-Chatelier's principle is

Le-Chatelier principle is not applicable to

Le-blanc process is employed in the manufacturing of

LDPE is a homopolymer, while nylon 6, 6 is a copolymer. Explain

ldentify the monohydrie unsaturated alcohol.

ldentify the incorrect statement(s)?

Layers of carbon atoms in graphite are held together by :

Law of raciprocd proportions can be used to determine :

Law of multiple proportion was given by

Lead is present in petrol in the from of _as_agent.