This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
In a Homogenous catalysis:- |
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Answer» the catalyst and the REACTANTS should be gases |
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| 2. |
In a hydrogen atom , in transition of electron a photon of energy 2.55 eV is emitted , then the change in wavelenghtof the eletron is |
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Answer» `3.32Å` `4 to 2` `lambda_(4)=(2pir_(4))/(4)""lambda_(2)=(2pir_(2))/(2)` `lambda_(4)lambda_(2P)=2pi[(0.529(4)^(2))/(1xx4)-(0.529(2)^(2))/(2)]` =`2pi(0.529)(2)` `=4pir_(1)`=`6.64 Å` |
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| 3. |
In a historical experiment to dtermine Planck's constant, a metal surface was irradiated with light of different wavelengths. The emitted photoelectron energies were measured by applying a stopping potential. The relevant data for wavelength (lamda) of incident light and the corresponding stopping potential (V_(0)) are given below Given that c=3xx10^(8)ms^(-1) and e=1.6xx10^(-19)C, Planck's constant (in units of J s) found from such an experiment is: |
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Answer» `6.0xx10^(-34)` `(hc)/(LAMDA)=E_(0)+eV_(0)` . . . .(i) Here, kinetic ENERGY of photoelectron `((1)/(2)mv^(2))=eV_(0)` `(hxx3xx10^(8))/(0.4xx10^(-6))=E_(0)+1.6xx10^(-19)xx2` . . . .(ii) `(hxx3xx10^(8))/(0.4xx10^(-6))=E_(0)+1.6xx10^(-19)xx1` . . . .(III) Substracting eq. (iii) from eq. (ii) we get `h[10^(15)-0.75xx10^(15)]=1.6xx10^(-19)` ltBrgt `hxx0.25xx10^(15)=1.6xx10^(-19)` `h=6.4xx10^(-34)`Js |
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| 4. |
In a hexagonal close packed (hcp) structure of spheres, the fraction of the volume occupied by the sphere is A.In a cubic close packed structure, the fraction is B. The relation for A and B is |
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Answer» `A=B` |
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| 5. |
In a H-atom, the transition takes place from L to K shell. If R = 1.08 xx 10^(7) m^(-1), the wave length the light emitted is nearly |
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Answer» 4400 Å |
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| 6. |
In a group with decrease in electronegativity the metallic character (a)decreases across a period(b)ncreases down the group(c )does not very |
| Answer» Answer :b | |
| 7. |
In a group from top to bottom effective nuclear charge |
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Answer» INCREASES |
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| 8. |
Writeanytwopropertieswhichare decreasedfromtoptobottomin agroup? |
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Answer» increaes |
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| 9. |
In a gobar gas plant, gobar gas in obtained by bacterial fermentation of animal refuse. The main combustible gas present in the gobar is found to be methane ( 80% by weight) whose heat of combustion is 809kJ mol^(-1)) . How much gobar gas would have to produced per day for a village of 100 families, if the average consumption of a family is 20,000kJ per dayto meet all its energy requirements . |
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Answer» Solution :Total energy requirements for 100 families per day `= 20,000 xx 100kJ = 2 xx 10^(6) kJ` Methane `(CH_(4))` undergoes combustion as follows `:` `CH_(4)(g) rarr 2O_(2)(g) rarr CO_(2)(g) + 2H_(2)O(L), Delta H = - 809 kJ MOL^(-1)` For 809 kJ of energy , `CH_(4)`REQUIRED`=16g` ( Molar mass of `CH_(4) = 16 g mol^(-1))` For ` 2 xx 10^(6)` kJ mol energy, `CH_(4)` required `(16)/(809) xx 2 xx 10^(6)g = 39.56kg` As gobar gas contains `80%` by weight of methane , therefore gobar gas required`=(100)/(80) xx 39.56 kg` `= 49.45kg` |
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| 10. |
In a glass tube columns of water and mercury appear as shown. This is best attributed to the differences in their: |
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Answer» DENSITIES |
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| 11. |
In a given shell the order of screening effect is |
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Answer» <P>`sgtpgtdgtf` |
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| 12. |
In a gaseous reaction the volume ratio of reactants and product is in agreement with their molar ration Volume of gas in inversely proportional to its mole at definite pressure and temperature . |
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Answer» <P> Solution :`V PROP` moles at CONSTANT `P,T` . |
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| 13. |
50.0 kg of N_(2)(g) and 10.0 kg of H_(2)(g) are mixed to produce NH_(2)(g). Calculate the NH_(2)(g) formed. Identify the limiting reagent in the production of NH_(3) in this situation. |
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Answer» Solution :The gasesous phase chemical equation for the production of ammonia is GIVEN as `N_(2)+3H_(2) to 2NH_(3)` 1 mole of `N_(2)="3 moles of "H_(2)` 28kg of `N_(2)=(2 XX 3)" kg of "H_(2)` 46.67 kg of `N_(2)` =10 kg of `H_(2)` 50kg of `N_(2)=10.71"kg of "H_(2)` Hence, HYDROGEN is the limiting reagent. 3 moles of `H_(2)="2 moles of "NH_(3)` 10 kg of `H_(2)=?` Maximum amount of ammonia produced is `(2 xx 17 xx 10)/(3 xx 2)=56.6kg` |
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| 14. |
In a gaseous mixture at 4 atm pressure, 25% of molecules are Nitrogen, 40% of molecules are carbon dioxide and the rest are oxygen. The partial pressure of oxygen in the mixture is |
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Answer» 1.40 ATM |
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| 15. |
In a gas lighter, mechanical energy is converted into electrical energy by using crystals of barium titanate. Barium titanate is |
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Answer» piezoelectric but not ferroelectric |
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| 16. |
In a gas phase reaction, 50 kg of nitrogen and 10 g of hydrogen are mixed to produce ammonia. Identify the limiting reagent. Calculate the maximum amount of ammonia produced. |
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Answer» Solution :The gaseous PHASE CHEMICAL equation for the PRODUCTION of ammonia is given as `N_(2)+3H_(2)rarr2NH_(3)` 1 mole of `N_(2)-=` moles of `H_(2)` `"28 kg of "N_(2)=(2XX3)" kg of "H_(2)` `"46.67 kg of "N_(2)="10 kg of "H_(2)` `"50 kg of "N_(2)="10.71 kg of "H_(2)` Hence, hydrogen is the limiting reagent, `"3 moles of "H_(2)="2 moles of "NH_(3)` `(3xx2)" kg of "H_(2)=(2xx17)" kg of "NH_(3)` `"10 kg of "H_(2)=?` Maximum amount of ammonia produced is `=(2xx17xx10)/(3xx2)=56.6kg` |
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| 17. |
In a fuel cell (device used for producing electricity directly from a chemical reaction )methanol is used as a fuel and oxygen gas is used asan oxidizer. The standard enthalpyof combustion of methanol is -721kJ mol^(-1) . The standard free energiesof formation of CH_(3)OH(l, CO_(2)(g) andH_(2)O(l) are- 166.3 , -394.4 and - 237 .1 kJ mol^(-1) respectively. The standard entropy change accopanying the cell reaction willbe |
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Answer» `+ 24.11 JK^(-1)` or `DeltaS^(@) = (DeltaH^(@) - DeltaG^(@))/( T)` ,brgt `= (- 726.0 - ( - 720.3) KJ mol^(-1))/(298K)` ` = - ( 5.7 kJ mol^(-1))/( 298K) = - ( 5700Jmol^(-1))/(298K)` `=- 19.1 JK^(-1) mol^(-1)` |
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| 18. |
In a fuel cell (device used for producing electricity directly from a chemical reaction )methanol is used as a fuel and oxygen gas is used asan oxidizer. The standard enthalpyof combustion of methanol is -721kJ mol^(-1) . The standard free energiesof formation of CH_(3)OH(l, CO_(2)(g) andH_(2)O(l) are- 166.3 , -394.4 and - 237 .1 kJ mol^(-1) respectively. The standard internal energy change of the cell reaction will be |
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Answer» `-727.24 KJ mol^(-1)` `= - 726 kJ mol^(-1) - (-(1)/(2))mol` `( 8.314 xx 10^(-3) kJ K^(-1) mol^(-1)) ( 298K)` `= - 726+ 1.24 kJ mol^(-1) = - 724 .76kJ mol^(-1)` |
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| 19. |
In a fuel cell (device used for producing electricity directly from a chemical reaction )methanol is used as a fuel and oxygen gas is used asan oxidizer. The standard enthalpyof combustion of methanol is -721kJ mol^(-1) . The standard free energiesof formation of CH_(3)OH(l, CO_(2)(g) andH_(2)O(l) are- 166.3 , -394.4 and - 237 .1 kJ mol^(-1) respectively. The efficiencyof the fuel cell will be |
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Answer» `96.7 %` |
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| 20. |
In a fuel cell (device used for producing electricity directly from a chemical reaction )methanol is used as a fuel and oxygen gas is used asan oxidizer. The standard enthalpyof combustion of methanol is -721kJ mol^(-1) . The standard free energiesof formation of CH_(3)OH(l, CO_(2)(g) andH_(2)O(l) are- 166.3 , -394.4 and - 237 .1 kJ mol^(-1) respectively. The standard free energy change of the reaction will be |
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Answer» `-597.8 kJ mol^(-1)` `CH_(3)OH(l) + (3)/(2) O_(2)(g) rarr CO_(2)(g) + 2H_(2)O(l) ` `Delta_(R)G^(@) = SigmaDelta_(f)G^(@)(` PRODUCTS) - `SigmaDelta_(f)G^(@)(`REACTANTS) `= [ Delta_(f)G^(@) ( CO_(2) +2Delta_(f) G^(@) (H_(2)O)] -[Delta_(f)G^(@) (CH_(3)OH)+(3)/(2)Delta_(f)G^(@) (O_(2))]` `= [( - 394.4) + 2 ( - 237.1) ] - [ - 166.3 + (3)/(2) (0)]` `=- 702 . 3 kJ mol^(-1)` |
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| 21. |
In a face centred cubic lattice, atom A occupies the corner positions and atom B occupies the face centre positions . If one atom of B is missing from one of the face centred points, the formula of the compound is : |
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Answer» `AB_2` Contribution by atoms B on the face centres =`5xx1/5=5/2` (Total atoms on face centres=6. As ONE ATOM is missing, atoms actually present=5) `therefore` Ratio of A:B=`1:5/2=2:5` HENCE, FORMULA =`A_2B_5` |
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| 22. |
In a face centred cubic lattice, atom A occupies the corner positions and atom B occupies the face centre positions. If one atoms of B is missing from one of the face centred points, the formula of the compound is : |
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Answer» `AB_(2)` ` 4= 8 xx 1/8 =1 ` Contribution by atoms B on the FACE CENTRES ` 5 xx 1/2 = 5/2 ` ( Total atoms on face centres = 6. As one atoms is missing , atoms actually present = 5) : Ration of A: B = ` 1 : 5/2 = 2: 5` Henece, formula ` = A_(2)B_(5)` |
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| 23. |
In a face centred cubic lattice, atom A occupies the corner positions and atom B occupies the face centre positions. If one atom of B is missing from one of the face centred points, the formula of the compound is |
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Answer» `A_(2)B` |
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| 24. |
In a face centred cubic lattice, atom A occupies the corner positionsand atom B occupies the face centre positions.If one atomof B is missing from one of the face centred points. |
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Answer» `A_(2)B` Number of B atoms per unit cell =`(6-1)/2=2.5` Formula of the compound =`A_(1)B_(2.5)orA_(2)B_(5)` |
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| 25. |
In a face centredcubic lattice, a cell is shared equally by how many unit cells ? |
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Answer» 4 |
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| 26. |
In a face-centred cubic crystal, the nearest neighbour distance is ___________ times the edge of the crystal |
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Answer» |
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| 27. |
In a face centred cubic cell, an atom at the face centre is shared by: |
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Answer» 4 UNIT CELL |
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| 28. |
In a face centered cubic lattice atoms A are at the corner points and atoms B at the face centered points. If atoms B is missing from one of the face centered points, the formula of the ionic compound is |
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Answer» `AB_(2)` |
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| 29. |
In a exothermic reaction, heat isevolved , andsystem losses heat to the surrounding . For such system: |
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Answer» `q_(q)`WIL be negative |
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| 30. |
In a Dumas nitrogen estimation method, 0.30 g of an organic compound gave 50 cm^(3) of N_(2) collected at 300 K and 715 mm Hg pressure. Calculate the percentage composition of nitrogen in the compound. (Vapour pressure of water at 300 K is 15 mm Hg) |
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Answer» Solution :`P_(1)=715-15=700 mm HG` , `P_(2)=760 mm Hg` `(P_(1)V_(1))/(T_(1))=(P_(2)V_(2))/(T_(2))` `T_(1)=300 K` , `T_(2)=273 K` , `V1=50 cm^(3)` , `V_(2)=?` `V_(2)=(700 xx 50 xx 273)/(300 xx 760)=41.9 cm^(3)` `"% of N"=(28)/(22400) xx 41.9 xx (100)/(W)=17.46%` |
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| 31. |
In a electrochemical cell |
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Answer» POTENTIAL energy changes into KINETIC energy |
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| 32. |
In a cubic vessel of side length 5 cm, a Helium molecule moving with a velocity 10^5 cm/sec in X-direction then rate of change in momentum in X-direction is (in g cm/sec) |
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Answer» `2.56 XX 10^(-14)` |
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| 33. |
In a cyclotrimetaphosphoric acid molecule, how many single and double bonds are present ? |
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Answer» 3 DOUBLE bonds , 9 SINGLE bonds |
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| 34. |
In a crystalline solid, anions B are arranged in a cubic close packing. Cations A are equally distrilbuted between octahedral and tetrahedral voids. If all the octahedral voids are occupied, what is the formula of the solid ? |
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Answer» Solution :Suppose the number of anions B = n. Then number of OCTAHEDRAL voids = n . Number of tetrahedral voids = 2n. As octahedral and tetradhedral voids are equally occupied by cations A and all the octahedral voids are occupied (given)THEREFORE, n capitan A are PRESENT in octahedral voids and n cationsA are present in tetrahedral voids. In other WORDS, correshponding to n anions B , there are n +n = 2n cations A. Thus, A and anuions B are in the ratio 2n: n =2 : 1 hence, the FORMUAL of the solid will be `A_(2) B` . |
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| 35. |
In a crystalline solid, anions B are arranged in a cubic close packing. Cations A are equally distributed between octahedral and tetrahedral voids. If all the octahedral voids are occupied, what is the formula of the solid ? |
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Answer» SOLUTION :Suppose the number of anions B=n . Then number of octahedral voids=n Number of TETRAHEDRAL voids =2n As octahedral and tetrahedral voids are equally occupied by cations A and all the octahedral voids are occupied (given ), therefore n cations A are present in octahedral voids and n cations A are present in tetrahedral voids. In other words, CORRESPONDING to n anions B, there are n+n=2n cations A . THUS, cations A and anions B are in the ratio 2n:n=2:1 . Hence , the formula of the solid will be `A_2B` |
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| 36. |
In a crystalline solid, W atoms are at corners, O atoms at edge centres and Na at cube centre, The formula of solid is |
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Answer» `Na_(4)WO_(3)` O (at edges) `=12xx(1)/(4)=3` Na (at centre )=1 `therefore` FORMULA is `NaWO_(3)` |
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| 37. |
In a crystal of an ionic compound, the ions B form the close packed lattice and the ions A occupy all the tetrahedral voids. The formula of the compound is |
| Answer» SOLUTION :The number of tetrahedral voids is two PER ATOM of the crystal in a close packed structure. Since tetrahedral voids are occupied by A ions, there are two A ions per B ion inthe crystal.The formula of the compound is `A_(2)B`. | |
| 38. |
In a crystal, all the lattice sites are found to be occupied by covalent molecules. To which kind of solid does it belong ? |
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Answer» Ionic |
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| 39. |
In a crystal, Frenkel defect is not shown by alkali metal halides but silver halides show. Why ? |
| Answer» Solution :Frenkel DEFECT is found in silver HALIDES due to SMALL size of `Ag^+` ION which can enter into interstitial site. It is not found in alkali metal halides, as the alkali metal ions are too big to fit into the interstitial SITES. | |
| 40. |
In a crystal, Frenkel defect is not shown by alkali metal halides buy sliver halides show. Why ? |
| Answer» Solution :FRENKEL defect is found in sliver HALIDES due to small size of `Ag^(+)` ion which can enter into interstitial SITE. It is not found in ALKALI metal halides, as the alkali metal ions are too BIG to fit into interstitial sites. | |
| 41. |
In a container of constant volume at a particular temparature N_(2) and H_(2) are mixed in the molar ratio of 9:13. The following two equilibria are found o be coexisting in the container N_(2)(g)+3H_(2)(g)harr2NH_(3)(g) N_(2)(g)+2H_(2)(g)harr N_(2)H_(4)(g) The total equiibrium pressure is found to be 305 atm while partial pressure of NH_(3)(g) and H_(2)(g) are 0.5 atm and 1 atm respectivly. Calculate of equilibrium constants of the two reactions given above. |
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Answer» Solution :Let the initial PARTIAL pressure of `N_(2)` be `9P` and `13P` respectively Total pressure`=P_(N_(2))+P_(H_(2))+P_(NH_(3))+P_(N_(2)H_(4))=3.5` ATM `(9P-x-y)+(13P-3x-2y)+2x+y=3.5`atm .....(1) ` P_(NH_(3))=2x=0.5` atm .....(2) `P_(H_(2))=(13P-3x-2y)= 1` atm ....(3) from (1) `implies(9P-x-y)+1 ` atm `+0.5+y=3.5` `implies(9P-x)=2` atm so `9P=2.25` `P=0.25` atm from (3) equation `2y=1.5` `y=0.75` atm so `P_(N_(2))=9P-x-y=1.25` atm `P_(H_(2))=1` atm `P_(NH_(3))=0.5` atm `P_(N_(2)(H_(4))=0.75` atm So, `K+(P_(1))=(P_(NH_(3))^(2))/P_(H_(2)^(3).P_(N_(2)))=(0.5xx0.5)/(1xx1xx1xx1.25)=0.2atm^(-2)` `K_(P_(2)=P_(N_2H_(4))/P_(N_(2).P_(H_(2))^(2))=(0.75)/(1xx1xx1.25)=0.6 atm^(-2)` |
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| 42. |
In a container m g of a gas is placed. After some time some gas is allowed to escape from container. The pressure of the gas becomes half and its absolute temperature 2//3 rd. The amount of gas escaped is |
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Answer» Solution :We KNOW that `PV = w (RT)/(M)` `:. (P_(1))/(P_(2)) = (w_(1))/(w_(2)) (T_(1))/(T_(2))` `P_(1) = P, P_(2) = (P)/(2), T_(1) = T, T_(2) = (2)/(3) T` `w_(1) = m, w_(2) = m - x` `(P)/(P//2) = (m)/(m x) xx (T)/(2T//3)` `2 = (m)/(m - x) xx (3)/(2)` `4 (m - x) = 3m` `4 m - 4 x = 3m` `m = 4x` or `x = m//4` |
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| 43. |
In a constant volume calorimeter, 3.5 g of a gas with molecular weight 28 was burtn in excess oxygen at 298.0K. The temperaure of the calorimeter was found to increase from 298.0 Kto298.45 K due to the combustion process.Given that the heat energy capacityof the calorimeteris 2.5 kJ K^(-1),the numerical value for the enthalpy of combustion of the gas in kJ mol^(-1)is |
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Answer» |
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| 44. |
In a constant volume calorimeter, 3.5 g of a gas with molecular weight 28 was burnt in ress oxygen at 298 K. The temperature of the calorimeter was found to Increase from 298 K to 298.45 K due to the combustion process. Given that the calorimeter constant is 2.5 KJ K^(-1) .Calculate the enthalpy of combustion of the gas in "kJ mol"^(-1). |
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Answer» Solution :Given `T_i`=298 K `T_f` =298.45 K `k=2.5 kJ K^(-1)` m=3.5 g `M_m`=28 heat EVOLVED=`kDeltaT` `=k(T_f-T_i)` `=2.5 kJ K^(-1)(298.45-298)K` =1.125 kJ `DeltaH_C=1.125/3.5xx28 "kJ MOL"^(-1)` `DeltaH_C=9 "kJ mol"^(-1)` |
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| 45. |
In a constant pressure calorimeter, 224 mL of 0.1 M KOH (aq) solution is reacted with 50ml of 0.1 MH_(2)SO_(4)(aq) solution then increase in temperature of solution will be 9assume heat capacity of calorimeter is negligible): Given : Specific heat of solution =1cal/g-K Density of solution =1g/mL |
| Answer» ANSWER :a | |
| 46. |
In a conjugate pair of reductant and oxidant, the oxidant has |
| Answer» Solution :Higher O.N | |
| 47. |
In a conjugate pair of reductant and oxidant, the oxidant has "________________" |
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Answer» HIGHER OXIDATION number |
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| 48. |
In a concentration cell the |
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Answer» two electrodes are of different elements |
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| 49. |
In a compression process, P_("ext") is ………….. |
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Answer» <P>`(P_("INT")+DP)` |
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| 50. |
In a compound oxide ions are arranged in cubic close packing arrangement. Cations A occupy one-sixth of the tetrahedral voids and cations B occupy one-third of the octahdral voids. The formual of the compound is A_(x), B_(y), O_(z) then find the value of x + y + z |
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Answer» |
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