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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.
| 451. |
The temperature at which a real gas behaves like an ideal gas over an appreciable pressure range is called …………………… . |
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Answer» Correct Answer - Boyle temperature |
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| 452. |
Which type of intermolecular forces exist among the following molecules ? (i) `H_(2)S` molecules (ii) `H_(2)O` molecules (iii) `CL_(2)` and `C Cl_(4)` molecules (iv) `SiH_(4)` molecules (v) Helium atomms (vi) He atoms HCl molecules |
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Answer» (i) Dipole-dipole interactions (because `H_(2)S` is polar). (ii) Hydrogen bonding. (iii) London dispersion forces (because are non-polar). (iv) London dispersion forces (because `SiH_(4)` is non-polar ) (v) London dispersion forces (because He atoms have symmetrical electron clouds). (vi) Dipole-induced dipole forces (because HCl is polar while He atom has symmetrical electron cloud). |
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| 453. |
The temperature at which second virial coefficient of a real gas is zero is calledA. critical temperatureB. Boyle temperatureC. inversion temperatureD. eutetic point |
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Answer» Correct Answer - B The virial equation for a real gas is ` PV=A+(B)/(V)+…` At Boyle temperature, the gas shows ideal behaviour, i.e., PV=RT which is so only when A=RT and B=0. |
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| 454. |
In order to increase the volume of a gas by 10% the pressure of the gas should beA. decreased by 10%B. decreased by 1%C. increased by 10%D. increased by 1% |
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Answer» Correct Answer - A `P_(1)V_(1)=P_(2)V_(2)."If" V_(1)=V`, `V_(2)=V+(10)/(100)V=V+(V)/(10)=(11V)/(10)` `P_(1)V=P_(2)(11V)/(10) or (10)/(11)P_(1)=0.9 P_(1)` `:.` Decrease in pressure=10% |
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| 455. |
Which of the following represents largest pressure ?A. 1 atmosphereB. 1 barC. 10 pounds per square inchD. 1000 pascals or `N m^(-2)` |
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Answer» Correct Answer - A 1 atm =101325 Pa or N `m^(-2)` 1 bar `=10^(5)` Pa or N `m^(-2)`=0.987 atm 14.7 1b/sq inch =1 atmospheric pressure at sea level Thus, 1 atm represents the largest pressure. |
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| 456. |
The surface tension of which of the following liquid is maximum?A. `H_(2)O`B. `C_(6)H_(6)`C. `CH_(3)OH`D. `C_(2)H_(5)OH` |
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Answer» Correct Answer - A Surface tension of `H_(2)O` is maximum due to maximum hydrogen bonding in comparison to `C_(6)H_(6),CH_(3)OH,C_(2)H_(5)OH`. The order of H-bonding is `H_(2)Ogt CH_(3)OHgtC_(2)H_(5)OH` (benzene does not from H-bond). |
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| 457. |
The surface tension of a liquid is affected byA. intermolecular forces among the moleculesB. temperatureC. the addition of active agentD. All of the above |
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Answer» Correct Answer - D The factor which affect the surface tension of liquid are Surface tension is higher for the liquids having greater intermolecular forces between their molecules. Surface tension of the liquid decreases with increase in temperature. It is because with increase in temperature the intermolecular forces of attraction between liquid molecules decreases. Due to the addition of surface active agent, i.e., Surfactants (e.g., soap), surface tension decreases. |
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| 458. |
The surface tension of which of the following liquid is maximum?A. `H_(2)O`B. `CH_(3)OH`C. `C_(2)H_(5)OH`D. `C_(6)H_(6)` |
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Answer» Correct Answer - A Surface tension of `H_(2)O` is maximum due to maximum hydrogen bonding in comparison to `C_(6)H_(6),CH_(3)OH,C_(2)H_(5)OH` The order of H-bonding is `H_(2)OgtCH_(3)OHgtC_(2)H_(5)OH.` (Benze does not form H-bond) |
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| 459. |
A gas is liquefiedA. above critical temperature and below critical pressureB. below critical temperature and above critical pressureC. below critical temperature and pressureD. above critical temperature and pressure |
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Answer» Correct Answer - B Every substance has a critical temperature `(T_(c ))` above which its gas form cannot be made to liquefy , no matter how great at which a substance can exist as a liquid. The minimum pressure that must be applied to bring about liqueficiation at the critical temperature is called the critical pressure `(p_(c))`. |
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| 460. |
The surface tension of which of the following liquid is maximum?A. `C_(2)H_(5)OH`B. `CH_(3)OH`C. `H_(2)O`D. `C_(6)H_(6)` |
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Answer» Correct Answer - C Surface tension of `H_(2)O` is maximum due ot maximum hydrogen bonding in comparison to `C_(2)H_(5)OH, CH_(3)OH, H_(2), and C_(6)H_(6)`. The order of `H`-bonding is `H_(2)O gt CH_(3)OH gt C_(2)H_(5)OH` ( Benzene does not form `H`-bond) |
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| 461. |
As per Charles law which of the following is/are correctA. Pressure remains definiteB. Mass remains definiteC. volume is proportional to the absolute temperatureD. All of the above are correct |
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Answer» Correct Answer - D `(V)/(T)=` constant (`P` and mass are constant) |
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| 462. |
If a gas expands at constant temperature, it indicates thatA. kinetic enrgy of the molecules decreasesB. pressure of the gas increasesC. kinetic energy of the molecules remains the sameD. number of molecules of the gas increase |
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Answer» Correct Answer - C According to the kinetic molecular theory , the average energy of gaseous molecules is directly proportional to the absolute temperature of the sample. |
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| 463. |
If a gas expands at constant temperature, it indicates thatA. kinetic energy of molecules decreasesB. pressure of the gas increasesC. kinetic energy of molecules remains the sameD. number of the molecules of gas increases |
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Answer» Correct Answer - C `KE=(3)/(2)RT` (for one mole of a gas) As, the kinetic energy of a gaseous molecule depends only on temperature, thus at constant temperature, the kinetic energy of the molecules remains the same. |
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| 464. |
If a gas expands at constant temperature, it indicates thatA. Pressure of the gas increasesB. number of the molecules of gas increasesC. kinetic energy of molecules remains the sameD. kinetic energy of molecules decreases |
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Answer» Correct Answer - C `KE= 3//2 RT`. ( At any constant temperature the `KE` of gaseous molecule remains the same.) |
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| 465. |
If a gas expands at constant temperature, it indicates thatA. kinetic energy of the molecules remians the sameB. number of the molecules of the gas increasesC. kinetic energy of the molecules decreasesD. pressure of the gas increases. |
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Answer» Correct Answer - A `KE prop T` and remains same at constant temperature. |
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| 466. |
Name the energy which arises due to motion of atoms of molecules in a body. How is this energy effected when the temperature is increased ? |
| Answer» This energy is known as thermal energy or average kinetic energy. It increase with the rise in temperature. | |
| 467. |
At what temperature will He atoms have the same r.m.s. speed as `H_(2)` molecules have at `27^(@)C`? |
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Answer» `U_(RMS) = sqrt((3RT)/(M))` `U_((H_(2))) = sqrt((3RT)/(2.0)) = sqrt((3R xx 300)/(2.0))` [Gram molecular mass of `H_(2) = 2.0 g mol^(-1)`] `U_((He)) = sqrt((3RT)/(4.0))` [Gram atomic mass of `He = 4.0 g "atom"^(-1)`] According to the available data : `U_((H_(2))) = U_((He)) :. sqrt((3R xx 300)/(2.0)) = sqrt((3RT)/(4.0))` Square both sides, `(3R xx 300)/(2.0) = (3RT)/(4.0)` or `T = 600 K` or `t = 600 - 273 = 327^(@)C` |
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| 468. |
A vessel of capacity `400 cm^(3)` contains hydrogen gas at 1 atm pressure at `7^(@)C`. In order to expel `28.57 cm^(3)` of the gas at the same pressure, to what temperature the vessel should be heated ? |
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Answer» Given `V_(1)=400` `T_(1)=7^(@)C=280.15K` `V_(2)=400-28.57=371.43cm^(3)` `T_(2)=?` `thereforeT_(2)=V_(2)T_(1)//V_(1)=300.15K` or `27^(@)C` |
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| 469. |
A 1 L flask cantaing vapours of methyl alcohol (molar mass 32) at a pressure was `10^(-3)` mm. How many molecules of mehtyl alcohol are left in the flask ? |
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Answer» `P_(1)=10^(-3)mm` `V_(1)=1000cm^(3)` `T_(1)=298K` For converting this volume to the volume at STP, apply `(P_(1)V_(1))/(T_(1))=(P_(2)V_(2))/(T_(2))` i.e., `(10^(-3)xx1000)/(298)=(760xxV_(2))/(273)` or `V_(2)=1.205xx10^(-3)cm^(3)` Now `22400cm^(3)` at STP `=6.02xx10^(23)` molecule `therefore1.205xx10^(-3)cm^(3)` at STP `=(6.02xx10^(23))/(22400)xx1.205xx10^(-3)` molecules `=3.24xx10^(16)` molecules |
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| 470. |
Which of the following contains gretest number of `N` atoms?A. `22.4 L` nitrogen gas at `STP`B. `500 mL` of `2.00 M NH_(3)`C. `1.00 mol` of `NH_(4)Cl`D. `6.02xx10^(23)` molecules of `NO_(2)` |
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Answer» (`a`) `22.4 L N_(2)` gas at `STP=1 mol N_(2)` `=N_(0)` molecules of `N_(2)` `=2N_(0)` atoms of `N` (`b`) `(500xx2)/(1000)=1 mol` of `NH_(3)` `=N_(0)` molecules of `NH_(3)` `=N_(0)` atoms of `N` (`c`) `1 mol` of `NH_(4)Cl=N_(0)` atoms of `N` (`d`) `6.02xx10^(23) NO_(2)` molecules `=6.02xx10^(23)` atoms of `N` |
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| 471. |
The average molecular speed is gretest in which of the following gas samples?A. `1.0 mol` of `O_(2)` at `560 K`B. `0.50 mol` of `Ne` at `500K`C. `0.20 mol` of `CO_(2)` at `440K`D. `2.0 mol` of He at `140 K` |
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Answer» Correct Answer - D Average molecular speed `= sqrt((8RT)/(pi M))` is dependent on T and M Thus, greater the value of `sqrt((T)/(M))`, the greater the molecular speed. Thus, Gas `=sqrt((T)/(M)) implies O_(2)=sqrt((560)/(32))= 4.18`, `Ne=sqrt((500)/(20))= 5.0`, `CO_(2)=sqrt((440)/(44))= 3.16` `He==sqrt(140)/(4)= 5.91` |
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| 472. |
Real gases behave ideally at:A. low temperature and low pressureB. low temperature, high pressureC. high temperature, low pressureD. high temperature, high pressure |
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Answer» Correct Answer - C Conceptual question. |
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| 473. |
The average molecular speed is gretest in which of the following gas samples?A. `1.0 mol N_(2)` at `560 K`B. `0.50 mol` of `Ne` at `500 K`C. `0.20 mol` of `CO_(2)` at `440 K`D. `2.0 mol` of `Ke` at `140 K` |
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Answer» `overline(u)=sqrt((8RT)/(pi M))` `overline(u) prop sqrt((T)/(M))` (`a`) `overline(u) prop sqrt((560)/(28))=sqrt(20)` (`b`) `overline(u) prop sqrt((500)/(20))=sqrt(25)` (`c`) `overline(u) prop sqrt((440)/(44))=sqrt(11)` (`d`) `overline(u) prop sqrt((140)/(4))=sqrt(35)` |
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| 474. |
Temperature at the foot of a mountian is `30^(@)C` and pressure is 760 mm, whereas at the top of the mountain these are `0^(@)C` and 710 mm. Compare the densities of the air at the foot and top of the mountain. |
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Answer» `rho=(PM)/(RT)` Hence `(rho_(1))/(rho_(2))=(P_(1))/(P_(2))xx(T_(2))/(P_(2))` `therefore(760mm)/(303K)xx(273K)/(710mm)=(0.964)/(1)` `thereforerho_(1):rho_(2)=0.964:1` |
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| 475. |
If we plot volume of a certain mass of a gas against temperature at constant pressure , we get a straight line intersecting on the negative side at `- 273 .^(@)C` which explains about absolute zero . This graph is know as A. isochorB. isothermC. isotoneD. isobar . |
| Answer» Correct Answer - D | |
| 476. |
When the temperature is increased, surface tension of water:A. IncreasesB. DecreasesC. Remains constantD. Shows irregular behaviour |
| Answer» On increasing the temperature, mobility of the molecules increases or vaporisation increases. Thus, the surface tension decreases. | |
| 477. |
Which of the following relationships for various gas laws is not correct ?A. `V_(t) = V_(0) + (V_(0))/(273)xx t`B. `(V_(1))/(T_(1)) = (V_(2))/(T_(2))` (constant P)C. `(P_(1))/(T_(1)) = (P_(2))/(T_(2))` (constant V)D. `(P_(1)T_(1))/(V_(1)) = (P_(2)T_(2))/(V_(2))` |
| Answer» Correct Answer - D | |
| 478. |
Write the kinetic gas equation and express it as `P = (2)/(3) E`, where E is the kinetic energy per unit volume. |
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Answer» For one mole of ideal gas the kinetic gas equation is `PV=(1)/(3)m u^(2)=(1)/(2)xx(2)/(3)m u^(2)=(2)/(3)xx(1)/(2)m u^(2)` or `P=(2)/(3)((1)/(2)(m u^(2))/(V))=(2)/(3)E` |
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| 479. |
What is the effect on the pressure of a gas if its temperature is increased at constant volume ?A. The pressure of the gas increases.B. The pressure of the gas decreases .C. The pressure of the gas remains same .D. The pressure of the gas remains same . |
| Answer» Correct Answer - A | |
| 480. |
Which of the following does not express the properties of gases ?A. Gases are highly compressible.B. Gases exert pressure equally in all directions .C. Gases have much higher density then liquids and solids .D. Gases mix evenly and completely in all proportions. |
| Answer» Correct Answer - C | |
| 481. |
What are the other elements besides noble gases which exist as gases under normal conditions ? Fill up the blanks by choosing the correct option . A. `{:("I II III IV V"),("H N O F Cl"):}`B. `{:("I II III IV V"),("H O N Cl F"):}`C. `{:("I II III IV V"),("H N O Cl I"):}`D. `{:("I II III IV V"),("He O N Cl Br"):}` |
| Answer» Correct Answer - A | |
| 482. |
Two atoms X and Y are non - polar and electrically symmetrical. What type of intermolecular forces of attraction can be developed between them ?A. Dipole - induced dipole forcesB. London forces or dispersion forcesC. Dipole - dipole forcesD. No forces of any kind. |
| Answer» Correct Answer - B | |
| 483. |
Under similar conditions which of the following gases will diffuse four times as quickly as oxygen ?A. `He`B. `H_(2)`C. `N_(2)`D. `D_(2)` |
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Answer» Correct Answer - B `(r_("gas"))/(r_(O_(2))) = sqrt((M_(O_(2)))/(M_("gas")))` `4 = sqrt((32)/(M_("gas"))) " or " 16 = (32)/(M_("gas"))` or `M_("gas") = (32)/(16) = 2, " i.e., " H_(2)` |
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| 484. |
Why do the gases occupy that entire space available to them ? |
| Answer» This is on account of very high kinetic energy of the gas molecules as a result of which they move at a very fast speed, | |
| 485. |
Why vegetables are cooked with difficulty at a hill station ? |
| Answer» The atmospheric pressure is less and so the boiling point is lowered. | |
| 486. |
Calculate the total pressure in a mixture of `4 g` of oxygen and `2 g` of hydrogen confined in a total volume of `1 L` at `0^(@)C`.A. `25. 184 atm`B. `31. 205 atm`C. `45.215 atm`D. `15. 210 atm` |
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Answer» Correct Answer - A No. of moles of `O_(2)=(4)/(32)= 0.125` No. of moles of `H_(2)=(2)/(2)` Total no. of moles `=1+0.125= 1.125= 1.125` `P=(nRT)/(V)= (1.125xx0.082xx273)/(1)=25.184 atm`. |
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| 487. |
Which of the following is correct option for the free expansion of an ideal gas under adiabatic condition ?A. `q!=0, Delta T=0, w=0`B. `q!=0, DeltaT=0, w=0`C. `q=0, Delta T=0, w=0`D. `q=0, Delta T lt0, w!=0` |
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Answer» Correct Answer - C For the free expansion of an ideal gas under adiabatic condition, `q=0, Delta T=0, w=0` |
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| 488. |
Which of the following statements is/are correct about real gases?A. The molecules do cause attractive forces on each another.B. They obey gas laws at low temperature and high pressure.C. They show deviations from ideal behaviour.D. The molecules have negligible mass. |
| Answer» Real gases have volume and force of attraction. | |
| 489. |
A thin glass bulb of 100 mL capacity is evacuated and kept in 2.0 L container at `27^(@)C` and 800 mm pressure. If the bulb implodes isothermally, calculate the new pressure in the container in kilopascals (kPa) |
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Answer» Initial volume of container `=2000-100=1900mL` volume after implosion `=2000mL` ltbr pressure `=(1900x800)/(2000)mm=760mm=101.325kPa` |
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| 490. |
For the non-zero value of the force of attraction between gas molecules, gas equation will beA. `PV=nRT-(n^(2)a)/(V)`B. `PV=nRT+nbP`C. `PV=nRT`D. `P=(nRT)/(V-b)` |
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Answer» when `(n^(2)a)/(V^(2))ne0` `(P+(n^(2)a)/(V^(2)))V=nRT` `PV+(n^(2)a)/(V)=nRT` `PV=nRT-(n^(2)a)/(V)` |
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| 491. |
Actual graph for the given parameters in (Q.25) will be A. `I`, `III`B. `I`, `II`C. `II`D. `I` |
| Answer» As `P` increases, `PV` also increases, hence graph `II`. | |
| 492. |
Arrange the gases, `H_(2) , N_(2), He, O_(2)` in increasing rate of diffusion. |
| Answer» The increasing rate of diffusion is `O_(2) lt N_(2) lt He lt H_(2)`. | |
| 493. |
At room temperature, ammonia gas at `1 atm` pressure and hydrogen chloride gas at `P atm` pressure are allowed to effuse through identical pin holes from opposite ends of a glass tube of `1 m` length and of uniform cross- section. Ammonium chloride is first formed at a distance of `60 cm` from the end through which `HCl` gas is sent in. What is the value of `P`? |
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Answer» Correct Answer - `2.20atm` |
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| 494. |
When heated above `916^(@)C`, iron changes its bcc crystalline from to fcc without the change in the radius of atom . The ratio of density of the crystal before heating and after heating is : |
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Answer» In body-centred packing, the efficiency of packing is `67.92%` . In the cubic packing, the packing efficiency is 74.02%. Let `rho_(1)` be the density when packing efficiency is 74.02% and `rho_(2)` is the density when packing efficiency is 67.92% `(rho_(2))/(rho_(1))=(67.92)/(74.02)=0.918` |
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| 495. |
The volume of atoms present in a fcc unit cell of a metal (r=atomic radius).A. `(16)/(3)pir^(3)`B. `(12)/(3)pir^(3)`C. `(24)/(3)pir^(3)`D. `(20)/(3)pir^(3)` |
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Answer» (a) Total number of atoms in the unit cell fcc=4 Total volume of an atom `(4)/(3)pir^(3)xx4 "["V=(4)/(3)pir^(3)"]"` `(16)/(3)pir^(3)` |
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| 496. |
Aluminium metal forms a cubic close-packed crystal structure. Its atomic radius is `125xx10^(-12)`m. (a) Calculate the length of the side of the unit cell. (b) How many such unit cells are there in `1.00 m^3` of aluminium ? |
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Answer» Correct Answer - (a)354 pm (b)`2.25xx10^28` ccp=fcc. For fcc, `r=a/(2sqrt2)` or `a=2sqrt2r=2xx1.414xx125xx10^(-2) m =354xx10^(-12) m`=354 pm Volume of one unit cell =`(354xx10^(-12)m)^3=4.436xx10^(-29) m^3` `therefore` No. of unit cell in 1 `m^3=1/(4.436xx10^(-29))=2.25xx10^28` |
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| 497. |
A metal crystallizes in `bcc` lattice. The percent fraction of edge length not covered by atom isA. 0.114B. 0.104C. 0.134D. 0.124 |
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Answer» (c ) Edge length not covered by atom=-2r "["therefore "For" bcc, r+(sqrt3)/(4)a"]" `a=-2xx(sqrt3)/(4)a=a[(2-sqr3)/(2)]` `therefore "% of fraction not covered"=(a[[2-sqrt3)/(2)]xx100)/(a)` |
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| 498. |
Which of the following is true about gaseous state?A. Thermal energy=Molecular attractionB. Thermal energy gt gt Molecular attractionC. Thermal energy lt lt Molecular attractionD. Molecular forces gt gt Those in liquids |
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Answer» Correct Answer - B It is characteistic of gases, i.e., Thermal energy gt gt molecular attraction. |
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| 499. |
Assertion: The increase in compressibility factor with increasing pressure in due to `a`. Reason: `Z= 1+(bP)/(RT)` for real gas can be obtained by neglecting `a//V^(2)` term in van der Waals equation.A. If both assertion and reason are true and the reason is the correct explanation of the assertion.B. If both assertion and reason are true but reason is not the correct explanation of the assertion.C. If assertion is true but reason is false.D. If assertion is false but reason is true. |
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Answer» Correct Answer - D At high pressure `Z=1+(bP)/(RT)`. |
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| 500. |
The rate of diffusion of hydrogen is about:A. one-half that of heliumB. 1.4 times that of heliumC. twice that of heliumD. four times that of helium. |
| Answer» Correct Answer - B | |