52671 + Interview Questions in Chemistry in Class 11

1.	Define the term Entropy. What happens to Entropy when ice melts to liquid water?
Answer» ANSWER :It is DISORDERNESS of the SYSTEM. ENTROPY INCREASES.

Discussion

2.	Define the term 'bond order' and find bond order of O_(2).
Answer» SOLUTION :Bond order is half of the difference of the ELECTRONS present in the bonding and antibonding present in the bonding and antibonding molecular orbitals , i.e., Bond order = `(1)/(2) (N_(b) - N_(a))` E.C. of `O_(2) = [ sigma (1s)]^(2)[sigma ^() (1s)]^(2)[sigma (2s)]^(2)[sigma ^() (2s)]^(2)[sigma (2p_(Z))]^(2) [ pi(2p_(y))]^(2) [pi^(**)(2p_(x))]^(1) [pi(2p_(y))]^(1)` `therefore ` Bond order = `(1)/(2) (10 - 6) = 2`

Discussion

3.	Define the team thermodynamics process .
Answer» Solution :The method of operation which can bring about the change in the system is called THERMODYNAMIC process. Eg. : Heating ,COOLING, expansion, COMPRESSION, fusion, vaporization ETC.

Discussion

4.	Define the state of equilibrium.
Answer» SOLUTION :At a PARTICULAR stage, the rate of the reverse reaction is equal to that of the FORWARD reaction indicating a state of equilibrium.

Discussion

5.	Define the law of multiple proportions. Explain it with two examples. How does this law point to the existance of atoms ?
Answer» Solution :Law ofmultiple proportions was first studied by Dalton in 1803 which may defined as follows : When two or more ELEMENTS combine to form two or more chemical compounds, then the MASSES of one of the elements which combine with a fixed mass of the other, bear a simple RATIO to one another . e.g., hydrogen combines with OXYGEN to form two compounds, namely, WATER and hydrogen peroxide. `{:("Hydrogen",+,"Oxygen",rarr,"Water",),(""2g,,""16g,," " 18g,):}` `{:("Hydrogen",+,"Oxygen",rarr,"Hydrogen peroxide",),(" 2g",," 32 g",,"34 g",):}` Here, the masses of oxygen which combine with a fixed mass of hydrogen bear a simple ratio, i.e., `16:32` or `1:2` . As we know that, when compounds mixed in different proportion, then they form different compounds. In the aboveexamples when hydrogen is mixed with different proportion of oxygen, then they form water or hydrogen peroxide. It shows that there are constituents which combine in a definiteproportion. These constituents may be atoms. Thus, law of multiple proportions shows existence of atoms which combine into molecules.

Discussion

6.	Define the general formula of non-polar compound on the basis of given information, where the electronic configuration of valence shell for A and B are as follows (a) ns^(2)np^(3) (b) ns^(2)np^(5): (P) AB_(3) (Q) AB_(4) (R) AB_(5) (S) AB_(6)^(-)
Answer» <P>P,Q,R Q,R,S R,S,P S,P,Q Solution :`AB_(5)` has ONE lone PAIR at (A), so it will be polar.

Discussion

7.	Define the following terms in relation to crystalline solids : (i) Unit cell (ii) Coordination number.
Answer» ANSWER :(a) p-type(b) FERROMAGNETISM(c ) Impurity defect PRODUCING cation vacancies

Discussion

8.	Screening effect influences A) atomic radius B) Ionisation enthalpy C) electron gain enthalpy
Answer» Solution :(a) `MG(s) +1//2 O_(2) rarr MGO(exo)` (b) `MgO(s) rarrMg^(2+) (g) +O^(2-) (g) `(ENDO) (C) Mg(s) `rarr ` Mg (g) (endo), `1//2O_(2) rarr `O (g) (endo) (d) Mg `rarr Mg^(+) +E^(-) ` (endo) (e) `Mg^(+) (g) rarr Mg^(2+) +e^(-) ` (endo) (f) O(g) `+ e^(-) rarr O^(-)` (g) `O^(-) +e^(-) rarr O^(2-)`

Discussion

9.	Define the following terms: (a) Isothermal process (b) adiabatic process (c) isobaric proces (d) isochoric process.
Answer» Solution :(a) Isothermal process: It is defined as one in which the temperature constant, during the change from its initial to final states . (b) Adiabatic process: It is defined as one in which there is no EXCHANGE of heat (Q) between the system and surrounding during OPERATIONS. (c) Isobaric process: It is defined as one in which the PRESSURE of the system remains constant during its change from the initial to final state. (d) Isochoric process: It is defined as one in which the VOLUME of system remains constant during its change from initial to finalstate of the process.

Discussion

10.	Define the following terms.
Answer» Solution :(i) System : A system is defined as any portion of MATTER ( or universe ) under thermodynamics consideration which is separated from the rest of the universe by real or imaginary BOUNDARIES. (ii) Surroundings: Everything in the universe that is not a the part of system and can interact with system is CALLED as surroundings. (III) Boundary : Anything which SEPARATES the system from its surroundings is calld boundary.

Discussion

11.	Define the following:(i) Bond order (ii) Hybridisation (iii) sigma -bond
Answer» Solution :(i) Bond order: Bond order `= (N_(b)-N_(a))/(2)` The number of bondsformed between the two bonded atoms in a MOLECULE is called bond order. (ii) Hybridisation: It is a PROCESS of mixing of atomic orbitals of the same atom with comparable energy to form equal number of new equivalent orbitals with same energy. The resultant orbitals are called hybridised orbitals and they POSSESS maximum symmetry and definite ORIENTATION in space so as to minimise the force of repulsion between their electrons. (iii) `sigma`- bond When two atomic orbitals overlap linearly along the axis, the resultant bond is called sigma `(sigma)` bond.

Discussion

12.	Define the following. (a) Molar Heat of fusion (b) Molar Heat of vapourisation (c) Molar Heat of sublimation (d) Heat of Transition
Answer» Solution :a. Molar Heat of fusion: The molar heat of fusion is defined as " The change in ENTHALPY when one mole of a solid substance is converted into the liquid state at is melting POINT". For example heat of fusion of icecan be represented as `H_(2)O_((s))overset(273K)rarrH_(2)O_((l))DeltaH_("fusion")=+5.98KJ` b. Molar Heat of vapourisation : The molarheat of vapourisation is the define as "The change in enthalpy when one mole of liquid is converted into vapour or gaseous state at its BOILING point " For example , heat of vapourisation of water can be represented as. `H_(2)O_((l))overset(373K)rarrH_(2)O_((g))DeltaH_("vap")=+40.626KJ` c. Molar Heat of sublimation: Molar Heat of sublimation is defined as "The change in enthalpy when one mole of a solid is directly converted into the gaseous state at its sublimation temperature ". For example , the heat fo sublimation of iodine is represented as `I_(2_((s))) rarrI_(2_((g))) DeltaH_("sub")=+62.42KJ` Heat of Transaction : The Heat of transaction is defined as " The change in enthalpy when one mole of an element change Fromone ALLOTROPIC form to another. For example , the transaction of DIAMOND into graphite may be represented as `C_(("diamond"))rarrC_(("graphite"))DeltaH_("trans")=+13.81KJ` `S_(("monoclinic"))rarrS_(("rhombic "))DeltaH_("trans")=-0.067KJ`

Discussion

13.	Define the following(a) equivalent mass of an acid (b) equivalent mass of a base (c ) equivlent mass of an oxidising agent (d) equivalent mass of a reducingagent
Answer» Solution :a) Equivalent mass of an acid: Equivalent mass of an acid is the number OT parts by mass of the acid which contains 1.008 part by mass of replaceable hydrogen atom. Equivalent mass of an acid = `("MOLAR mass of the acid")/("Basicity of the acid")` (b) Equivalent mass of a base: ) Equivalent mass of a base: It is defined as the number of parts by mass of the base which contains one replaceable HYDROXYL ion or which completely neutralizes one gram equivalent of an acid. Equivalent mass of a base =`("Molar mass of the base")/(" Acidity of the base")` (c) Equivalent mass of an oxidising agent : It is defined as the number of pails by mass of an oxidising agent which can FURNISH 8 parts by mass of oxygen for OXIDATION. (d) Equivalent mass of a reducing agent: It is defined as the number of parts by mass of the reducing agent which is completely oxidised by 8 parts by mass of oxygen or with one equivalent of any oxidising agent.

Discussion

14.	Define the Elevation of boiling point
Answer» Solution :When a nonvolatile solute is added to a pure SOLVENT at its boiling point .the vapour PRESSURE of the solution its LOWERED below.1 atm . To bring the vapour pressure again to1 atm .The temperature of the solution has to be INCREASED As a RESULT . The solution boils at a higher temperature `(T_b) ` than the boiling point of the pure solvent ` (T^(@)_b) ` .This increase in the boiling point is known as elevation of boiling point Elevention of boiilng point ` (Delta T_b) =T_b -T^(@) _b`

Discussion

15.	Define the calorific value of food. What is the unit of calorific value?
Answer» Solution :(i)The calorific VALUE of food is DEFINED as the amount of heat produced in calories (or Joules) when one GRAM of food is completely burnt. (ii) Unit of calorific value (a)`Cal g^(-1)` (b)`J Kg^(-1)`

Discussion

16.	Define the Boiling point
Answer» Solution :Boiling points is an importantphysical property of a LIQUID.The boiling POINT of a liquid isthe temperature at which its vapour pressure BECOMES EQUAL to the atmospheric pressure (1 atm)

Discussion

17.	Define the bond length. (Exercise - 4.10) OR What is bond length ? How it ls measured ?
Answer» SOLUTION :Bond LENGTH is defined or the equilibrium distance between the nuclei of two BONDED atom in a molecule. Bond lengths are measured by SPECTROSCOPIC, X-ray-diffraction and electron-diffraction techniques.

Discussion

18.	Define surface tension.
Answer» SOLUTION :Surface TENSION is defined as force per unit length acting PERPENDICULAR to the tangential LINE on the surface. It is due to unbalanced ATTRACTIVE forces acting donwards

Discussion

19.	Define superconductivity of a substance .
Answer» SOLUTION :The property of a SUBSTANCE to OFFER no resistances to the flow of elctricity at a PARTICULAR temperature is CALLED superconductivity.

Discussion

20.	Define superconductivity of a substance.
Answer» SOLUTION :The property of a substance to offer no RESISTANCE to the flow of electricity at a particular TEMPERATURE is CALLED superconductivity .

Discussion

21.	Define sublimation. Give two examples.
Answer» Solution :The process of conversion of solid to vapour without MELTING or HEATING and on cooling the vapours GETTING back solids, such PHENOMENON is known as sublimation. e.g., Naphthalene, CAMPHOR.

Discussion

22.	Define stoichiometry and stoichiometric calculation.
Answer» SOLUTION :The word .stoichiometry. is derived from two Greek words - stoicheion ( meaning element) and metron ( meaning measure). Stoichiometry, thus, deals with the calculation of masses ( sometimes volumes also) of the reactants and the products involved in a CHEMICAL reaction. Before understanding how to calculate the amounts of reactants required or the products produced in a chemical reaction, LET us study what information is available from the balanced chemical equation of a given reaction. Let us consider the combustion of methane. A balanced equation for this reaction is given as : `CH_(4(g))+2O_(2(g)) rarr CO_(2(g))+2H_(2)O_((g))` Here, methane and dioxygen are called reactants and carbon dioxide and water are called products. Note that all the reactants and the products are gases in the above reaction and this has been indicated by letter (g) in the brackets next to its formula, Similarly, in the case of solids and LIQUIDS, (S) and (l) are written respectively. The coefficients 2 for `O_(2)` and `H_(2)O` are called stoichiometric coefficients. Similarly the coefficient for `CH_(4)` and `CO_(2)` is one in each case. Thus, From these relationships, the given data can be interconverted as follows: `"mass" hArr "mole" hArr "no. of molecules" ("mass")/("valume") = "pensity"`

Discussion

23.	Define fuse.
Answer» Solution :The isomers which have same bond connectivity but DIFFERENT arrangement of GROUPS or atoms in space are KNOWN as STEREOISOMERS. This phenomenon is known as stereoisomerism.

Discussion

24.	Calculate the standard entropy of formation DeltaS_(f)^(@) " of "CO_(2_((g))) . Given the standard entropies of CO_(2_((g))),C_((s)),O_(2_((g))) as 218.8,8.740and 205.60Jk^(-1) respectively .
Answer» Solution :Standard entropy of FORMATION is DEFINED as "the entropy of formation of 1 MOLE of a COMPOUNDFROM the elements under standard conditions. It is denoted as `DeltaS_f^0` We can calculate the value of entropy of a given compound from the values of `S^0` of elements `DeltaS_f^0=sum DeltaS_"products"^0 - sum DeltaS_"REACTANTS"^0`

Discussion

25.	Define standard entropy change.
Answer» SOLUTION :The absolute entropy of a substance at 298 K and one atmosphere PRESSURE is CALLED the standard entropy `S^(@)`.

Discussion

26.	Define standard entropy of formation.
Answer» SOLUTION :The STANDARD heat of formation of a compound is defined as "The change in enthalpy that takes place when one mole of a compound is formed from its elements, all substances being in their standard states (298 K and 1 ATM pressure).

Discussion

27.	Define standard heat of formation .
Answer» Solution :The standard heat of FORMATION of a compound is defined as " The change in enthalpy that takes PLACE when ONE mole of a compound is formed from its elements , all substances being in their standard STATES ( 298 K and I pressure) .

Discussion

28.	Define Standard Enthalpy of Vapourisation.
Answer» Solution :Amount of HEAT required to vapourize one mole of a liquid at constnat temeprature under STANDARD pressure (1 bar) is called standard enthalpy of VAPORIZATION.

Discussion

29.	Define standard enthalpy changes .
Answer» SOLUTION :The standard enthalpy of a reaction is the enthalpy CHANGE for a reaction when all the participating substances are present in their standard states. Standard conditions are DENOTED by adding the SUPERSCRIPT 0 to the symbol (AH) .

Discussion

30.	Specific heat capacity
Answer» Solution :SPECIFIC heat capacity of a system is DEFINED as the heat absorbed by ONE gram of a substance in raising its temperature by one Kelvin at a specified temperature. `Cm=q/(T_2-T_1)` Where C=specific heat capacity,q=amount of heat absorbed, m=mass and `T_1,T_2`= temperatures.

Discussion

31.	Define solution.Explain with an example.
Answer» Solution :(i) A solution is a homogeneous mixture of two or more substances consisting of atoms, IONS or molecules. (II) For example, when a SMALL amount of NaCl is dissolved in water, a homogeneous solution is obtained. In this solution, `Na ^(+) and Cl ^(-)` ions are uniformly distributed in water. Here NaCl is the SOLUTE and water is the solvent.

Discussion

32.	Define solution. Explain with an example.
Answer» Solution :A solution is a homogeneous mixture of two or more substances, consisting of atoms, ions or molecules. The compound that is PRESENT in largest amount in a homogenous mixture is called the SOLVENT, and the other are solutes. For EXAMPLE, when a small amount of NACL is dissolved in water, a homogenous solution is obtained. In this solution, `Na^(+)` and `Cl^(-)` ions are uniformly distributed in water. Here water is the solvent as the amount of water is more compared to the amount of `NaCl` present in this solution, and the NaCl is the solute.

Discussion

33.	Define solubility product of weak electrolyte.
Answer» Solution :SOLUBILTY product of WEAK electrolyte is defined as the product of MOLAR concentration of ions of electrolyte raised to APPROPRIATE power within saturated solutioin of that electrolyte.

Discussion

34.	Define -soil pollution.
Answer» Solution :Soil pollution is defined as the BUILD up of persistent TOXIC compounds, radioactive materials, chemical salts and disease causing agents in soil which have harmful effects on plant GROWTH animal health. Soil pollution affects the structure and fertility of soil, ground water quality and food CHAIN in biological ECOSYSTEM.

Discussion

35.	Define silicones.
Answer» Solution :Silicones are synthetic ORGANO silicon COMPOUNDS CONTAINING `R_(2) SiO` repeated units held together by Si - O - Si LINKAGES.

Discussion

36.	Define-Smog.
Answer» Solution :(i) Smog is a combination of smoke and fog which form DROPLETS that remains suspended in the air. (ii) Smog is a chemical mixture of GASES that forms a brownish yellow haze. It mainly consists of ground LEVEL ozone, oxides of nitrogen, volatile organic compounds, so, ACIDIC aerosols and some other gases.

Discussion

37.	Define smog.
Answer» Solution :(i) Smog is a combination of smoke and fog which FORM droplets that remains suspended in the air. (ii) Smog is a chemical MIXTURE of gases that forms a BROWNISH yellow haze. It mainly. consists of ground LEVEL ozone, oxides of nitrogen, volatile organic compounds, SO,. acidic aerosols and some other gases.

Discussion

38.	Define Reversible reaction with an example.
Answer» SOLUTION :A chemical REACTION in which an infinitesimally small change in any one of the variables (PRESSURE, Temperature, Concentration of REACTANT or product) of the reaction changes the direaction (forward or backward) of the reaction. It is represented by a half arrow MARK. An example is `H_(2)(g)+I_(2)(g)hArr2HI(g)`

Discussion

39.	Define resonance effect.
Answer» Solution :The resonance is a chemical phenomenon which is observed in CERTAIN ORGANIC compounds prossessing double bonds at a suitable position . Certain organic compounds can be represented by more than one structure and they differ only in the position of bonding and IRON PAIR of electrons. Such structures are called resonance structures (canonical structures) and this phonomenon is called resonance . This phenomenon is also called MESOMERISM or mesomeric effect.

Discussion

40.	Define electric resonance.
Answer» Solution :The SIMILAR structures in which the relative position of the atoms are same but they DIFFER in the position of bonding and lone pair of ELECTRONS are called RESONANCE structures and this PHENOMENON is called resonance.

Discussion

41.	Define reaction quotient.
Answer» SOLUTION :Under non-equilibrium conditions, REACTION quotient 'Q' is defined as the ratio of the product of ACTIVE masses of reaction PRODUCTS raised to the respective stoichiometric coefficients in the balanced chemical equation to that of the reactants. `Q=([C]^(l)[D]^(m))/([A]^(x)[B]^(y))`

Discussion

42.	Define Rate equation with an example.
Answer» Solution :An expression which relates the RATE (velocity) of the REACTION with change in CONCENTRATION of the reactant in a given interval of time. `+(d[A])/(dt)=(+1)/2(d[B])/(dt)=(-1)/3(d[c])/(dt)=(-1)/4(d[D])/(dt)`

Discussion

43.	Define Q value for a chemical equilibrium reaction.
Answer» Solution :Consider a HOMOGENEOUS reversible reaction `xA + YB HARR LC + mD` For the above reaction under non-equlibrium conditions , reaction quotient Q is defined as the ratio of the product of active masses of reaction produtsraised to the respective stoichiometric coefficients in the balanced chemical equation to that fo the REACTANTS. Under non equilibrium condtions. `Q = (d(lnk))/(dT) = (DeltaH^@)/(RT^2)`

Discussion

44.	Define PPM.
Answer» Solution :Expression : ` ("Number of part of the components ")/( " TOTAL number of part of all components ") xx 10 ^( 6) ` ` ("MASS of the solute ")/( "Mass of the solution ") xx 10 ^(6) ` Iilustration 50 mL of TAP water contains 20 mg of dissolved solids . The TDS value in ppm is ` ("Mass of the dissolved solids ")/( " Mass of the water ") xx 10 ^(6)` ` =( 20 xx10 ^(3)g)/( 50 g ) xx 10 ^( 6) =400 ppm `

Discussion

45.	Define polarization.
Answer» SOLUTION :The distortion of ELECTRON cloud of the anion by the CATION is CALLED polarization.

Discussion

46.	Define pK_(a) for weak acids.
Answer» SOLUTION :NEGATIVE logarithm to the base ten of the dissociation constant of an acid is called `pK_(a)` for the acid. `thereforepK_(a)=-log_(10)K_(a)`

Discussion

47.	Define pOH of a solution.
Answer» Solution :Negative logarithm to the BASE TEN of molar CONCENTRATION of HYDROXYL ions in the solution. `pOH=-log[OH^(-)](or)pOH=+"log"1/([OH^(-)])`

Discussion

48.	Define pK_(b) for a weak base.
Answer» Solution :Negative LOGARITHM to the base TEN of the dissociation constant of the base `(K_(b))` is CALLED `pK_(b)` for the base. `pK_(b)=-log_(10)K_(b)`.

Discussion

49.	Define pH scale.
Answer» SOLUTION :pH scale is a logarithmic scale used to express HYDROGEN ion concenreations. It gives pH range in acidic, BASIC and NEUTRAL solutions.

Discussion

50.	Define pH of a solution.
Answer» SOLUTION :Negative LOGARITHM to the base ten of molar CONCENTRATION of hydroxyl IONS in the solution. `pH=-log[H_(3)O^(+)](or)pH=+"log"1/([H_(3)O^(+)])`

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

Define the term Entropy. What happens to Entropy when ice melts to liquid water?

Define the term 'bond order' and find bond order of O_(2).

Define the team thermodynamics process .

Define the state of equilibrium.

Define the law of multiple proportions. Explain it with two examples. How does this law point to the existance of atoms ?

Define the general formula of non-polar compound on the basis of given information, where the electronic configuration of valence shell for A and B are as follows (a) ns^(2)np^(3) (b) ns^(2)np^(5): (P) AB_(3) (Q) AB_(4) (R) AB_(5) (S) AB_(6)^(-)

Define the following terms in relation to crystalline solids : (i) Unit cell (ii) Coordination number.

Screening effect influences A) atomic radius B) Ionisation enthalpy C) electron gain enthalpy

Define the following terms: (a) Isothermal process (b) adiabatic process (c) isobaric proces (d) isochoric process.

Define the following terms.

Define the following:(i) Bond order (ii) Hybridisation (iii) sigma -bond

Define the following. (a) Molar Heat of fusion (b) Molar Heat of vapourisation (c) Molar Heat of sublimation (d) Heat of Transition

Define the following(a) equivalent mass of an acid (b) equivalent mass of a base (c ) equivlent mass of an oxidising agent (d) equivalent mass of a reducingagent

Define the Elevation of boiling point

Define the calorific value of food. What is the unit of calorific value?

Define the Boiling point

Define the bond length. (Exercise - 4.10) OR What is bond length ? How it ls measured ?

Define surface tension.

Define superconductivity of a substance .

Define superconductivity of a substance.

Define sublimation. Give two examples.

Define stoichiometry and stoichiometric calculation.

Define fuse.

Calculate the standard entropy of formation DeltaS_(f)^(@) " of "CO_(2_((g))) . Given the standard entropies of CO_(2_((g))),C_((s)),O_(2_((g))) as 218.8,8.740and 205.60Jk^(-1) respectively .

Define standard entropy change.

Define standard entropy of formation.

Define standard heat of formation .

Define Standard Enthalpy of Vapourisation.

Define standard enthalpy changes .

Specific heat capacity

Define solution.Explain with an example.

Define solution. Explain with an example.

Define solubility product of weak electrolyte.

Define -soil pollution.

Define silicones.

Define-Smog.

Define smog.

Define Reversible reaction with an example.

Define resonance effect.

Define electric resonance.

Define reaction quotient.

Define Rate equation with an example.

Define Q value for a chemical equilibrium reaction.

Define PPM.

Define polarization.

Define pK_(a) for weak acids.

Define pOH of a solution.

Define pK_(b) for a weak base.

Define pH scale.

Define pH of a solution.