94420 + Interview Questions in Chemistry in Class 12

1.	It has been estimated that the total energy ratiated by sun is 3.8 xx 10^(26) j per second. The source of energy of stars is a thermonuclear reaction called nuclear fusion. Fusion reactions are not controlled. It is presumed that the energy of stars is due to two processes called proton-proton cycle and carbon-nitrogen cycle and carbon-nitrogen cycle. Fusion cannot take place at ordinary temperature. Thus, hydrogen bomb uses a small fission bomb, which on explosin causes the temperature to rise very high, about 10^(7) K. We have yet to see how a hydrogen bomb can be used for peaceful life-sustaining purpose. Energy released in the process of fusion is due to mass defect. It is also called Q-value Q = Delta mc^(2),Delta M = mass defect The binding energy per nucleon of ._(1)^(2)H and ._(2)^(4)He are 1.1 MeV and 7 MeV respectively. If two deuteron nuclei react to form a single helium nucleus, then the energy released is:
Answer» 13.9 MeV 26.9 MeV 23.6 MeV 19.2 MeV Answer :C

Discussion

2.	"Kg m"^(-1)s^(-2) is the unit of………………….. .
Answer» SOLUTION :PRESSURE

Discussion

3.	Isotropy.
Answer» Solution :The ABILITY of amorphous SOLIDS to EXHIBIT identical physical properties even though measured in DIFFERENT directions is called isotropy.

Discussion

4.	KF has NaCl structure. What is the distance between K^(+) and F^(-) in KF, if its density is 2.48 g cm^(-3) ?
Answer» Solution :For NACL type structure, Z=4, M = 39 +19=58.0g `mol^(-1)`, d=2.48 g `cm^(-3)` `a^3=(Z xx M)/(N_A xx d)=(4 xx 58.0)/(6.023 xx 10^(23) xx 2.48) = 15.53 xx 10^(-23) cm^3`: `a = 5.375 xx 10^(-8)` cm= 537.5 pm For NaCl type structure, a = `2 xx "interionic distance"`. `:.` Distance between K and `F^(-)` ions = `(537.5)/(2)` = 268.75 pm

Discussion

5.	Isotopes of oxygen with mass number less than 16 undergo beta^+emission. Assuming an equimolar mixture of ""^14Oand ""^15O,find the ratio of the nuclides at the end of one hour. Given that t_(1//2) (""^14O) = 71 s and t_(1//2) (""^15O) = 124 s . At what time will the above said ratio be equal to 0.25?
Answer» SOLUTION :`3.29 XX 10^(-7) , 332 s`

Discussion

6.	KF has NaCl structure. The edge length of its unit cell has been found to be 537.6 pm. The distance between K^(+) and F^(-) in KF is :
Answer» 537.6pm 268.8pm 1075.2pm cannot be calculated Solution :In KF, edge LENGTH is equal to `2(r_(K^(+))+r_(F^(-)))` so that, `r_(K^(+))+r_(F^(-))= ( 537)/( 2) = 268.8`PM

Discussion

7.	Isotopes of oxygen with mass number less than 16 undergobeta^+ emission. Assumingan equimolar mixture of ""^14Oand ""^15O , find the ratio of the nuclides at the end of one hour. t_(1//2) for ""^14O= 71 s, t_(1//2) for ""^15O=124 s.At what time will the ratio of ""^14Onuclei to ""^15Onuclei be equal to 0.25?
Answer» SOLUTION :`3.02 XX 10^(-7) , 332 s `

Discussion

8.	K_(f) for water is "1.86 K kg mol"^(-1). If your automobiles radiator holds 1.0 kg of water, how many grams of ethylene glycol (C_(2)H_(6)O_(2)) must you add to get the freezing point of the solution lowered to -2.8^(@)C?
Answer» 27 g 72 g 93 g 39 g Solution :`M_(2)=(1000K_(F)w_(2))/(w_(1)DeltaT_(f))` `therefore""62=(1000xx1.86xxw_(2))/(1000xx2.8)"or"w_(2)=93.3g`

Discussion

9.	Isotopes were discovered by
Answer» Aston Soddy Thomson Mullikan Answer :B

Discussion

10.	K_(f) for water is 1.86^(@)Cm^(-1). What is the molality of a solutionn which freezes at -0.192^(@)C? Assuming no change in the solute by raising the temperature, at what temperature will the solution boil ? (K_(b) for H_(2)O=0.515^(@)Cm^(-1))
Answer» SOLUTION :MOLALITY `=(DeltaT_(f))/(K_(f))` `=(0.192)/(1.86)=0.103m` Again `DeltaT_(B)=K_(b).m` …………(Eqn. 8) `=0.515xx0.103=0.0532^(@)C` Assuming the b.p. of pure water to be `100^(@)C` the b.p. of the solution will be `100.0532^(@)C`

Discussion

11.	Isotopes of same elemeents have the same number of
Answer» Protons Neutrons Deutrons None Solution :Isotopes of same ELEMENTS have the same NUMBER of protons but DIFFERENT number of neutrons.

Discussion

12.	KF has ccp structure . Calculate the radius of unit cell if the side of the cube or edge length is 400 pm . How many F ions and octahedral voids are there in this unit cell ?
Answer» SOLUTION :For ccp lattice `r=(sqrt2a)/(4) or r=(1.414xx"400 pm")/(4) or r=141.4" pm"` There are `4F^(-)` IONS and 4 octahedral VOIDS.

Discussion

13.	Isotopes are the atoms of same element, they have same atomic number but different mass numbers. Isotopes have different number of neutrons in their nucleus . If an element exists in two isotopes having atomic masses 'a' and 'b' in the ratio m:n, then average atomic mass will be (mxxa+nxxb)/(m+n) Different isotopes of same element have same position in the periodic table. the elemens which have single isotope are called monoisotropic elements. Greater is the percentage composition of an isotope, more will be its abundance in nature. .^(12)C and .^(14)C isotopes are found at 98% and 2% respectively in any sample. then, the number of .^(14)C atoms in 12g of the sample will be:
Answer» 1.5 mole atoms `1.032xx10^(22)` atoms `2.06xx10^(21)` atoms 2G atoms Answer :B

Discussion

14.	K_(f) for water is 1.86 K kg mol^(-1). If your automobile radiator holds 1.0 kg of water, how may grams of ethylene glycol (C_(2)H_(6)O_(2)) must you add to get the freezing point of the solution lowered to - 2.8^(@)C
Answer» 72 g 93 g 39 g 27 g Solution :`Delta T_(F)= i XX k_(f)xx m` `2.8=1xx1.86xx(x)/(62xx1)` `x=(2.8xx62)/(1.86)=93 GM`

Discussion

15.	Isotopes are the atoms of same element, they have same atomic number but different mass numbers. Isotopes have different number of neutrons in their nucleus . If an element exists in two isotopes having atomic masses 'a' and 'b' in the ratio m:n, then average atomic mass will be (mxxa+nxxb)/(m+n) Different isotopes of same element have same position in the periodic table. the elemens which have single isotope are called monoisotropic elements. Greater is the percentage composition of an isotope, more will be its abundance in nature. The ratio of mass of .^(12)C atom to that of an atom of element X(whose atomicity is four) is 1:9. the molecular mass of element X is:
Answer» 480 G `"mol"^(-1)` `432g "mol"^(-1)` `36 g "mol"^(-1)` `84g "mol"^(-1)` ANSWER :B

Discussion

16.	Isotopes are the atoms of same element, they have same atomic number but different mass numbers. Isotopes have different number of neutrons in their nucleus . If an element exists in two isotopes having atomic masses 'a' and 'b' in the ratio m:n, then average atomic mass will be (mxxa+nxxb)/(m+n) Different isotopes of same element have same position in the periodic table. the elemens which have single isotope are called monoisotropic elements. Greater is the percentage composition of an isotope, more will be its abundance in nature. Which of the following isotopes is/are used to decide the scale of atomic mass?
Answer» `._(6)^(12)C` `._(6)^(14)C` `_(8)^(16)O` `._(7)^(14)N` Answer :A::C::D

Discussion

17.	K_(f) for water is 1.86 K kg "mol"^(-1). If your automobile radiator holds 1.0 kg of water, how many grams of ethylene glycol (C_(2)H_(6)O_(6)) must you add to get the freezing point of the solution lowered to - 2.8^(@)C ?
Answer» 93 G 39 g 27 g 72 g Answer :A

Discussion

18.	Isotopes are the atoms of same element, they have same atomic number but different mass numbers. Isotopes have different number of neutrons in their nucleus . If an element exists in two isotopes having atomic masses 'a' and 'b' in the ratio m:n, then average atomic mass will be (mxxa+nxxb)/(m+n) Different isotopes of same element have same position in the periodic table. the elemens which have single isotope are called monoisotropic elements. Greater is the percentage composition of an isotope, more will be its abundance in nature. The isotopes of chlorine with mass number 35 and 37 exist in the ratio of. . . .. Its average atomic mass is 35.5.
Answer» `1:1` `2:1` `3:1` `3:2` ANSWER :C

Discussion

19.	KF crystallizes in fce structure like sodium chloride. calculate the distance between K^(+) and F^(-) in KF. ("given : density of KF is 2.48 g cm"^(-3))
Answer» Solution :`"DENSITY of KF"="2.48 g cm"^(-3)` `RHO=(nM)/(a^(3)N_(A))` N = 4 (For Fcc) `rho=(4xx58)/(a^(3)xx6.023xx10^(23))` `2.48=(4xx58)/(a^(3)xx6.023xx10^(23))` `a^(3)=(4xx58)/(2.48xx6.023xx10^(23))` `a^(3)=(232)/(14.93xx10^(23))` `a^(3)=15.54xx10^(-23)` `a="537.5 pm"` `d=(a)/(sqrt2)"(For fcc)"` `d=(537.5)/(1.414)` `d=380.12" pm"`

Discussion

20.	Isotope of which noble gas is isotonic (same number of neutrons) with Tritium?
Answer» Ne He Kr Rn Answer :B

Discussion

21.	K_f(+10)/K_tis known as :
Answer» Ratio of equilibrium constants TEMPERATURE coefficient Difference in temperature of REVERSIBLE reactions None of the above Answer :D

Discussion

22.	Ketoximes are oxidised into 2^(@)-nitroalkane by using
Answer» `kMnO_(4)` `K_(2)Cr_(2)O_(7) + dil.H_(2)SO_(4)` trifluoroperoxy acetic ACID PYRIDINIUM chlorochromate Answer :C

Discussion

23.	Isotope of uranium used in atomic bomb is
Answer» `._(92)^(237)U` `._(92)^(238)U` `._(92)^(239)U` `._(92)^(235)U` ANSWER :B

Discussion

24.	Ketoxime on oxidation by trifluoroperoxy acetic acid gives
Answer» `1^(@)` - NITROPARAFFINS `2^(@)` - nttroparaffins `3^(@)` - nitroparaffins `1 ^(@)` - amines Answer :B

Discussion

25.	Isotonic solutions must have the same………..
Answer» SOLTE density elevation in boilling point depression in freezing point SOLUTION :istonic SOLUTIONS have same MOLAR CONCENTRATION and therefore, same colligative properties. Options (c,d) are both correct.

Discussion

26.	Ketoximeon reductiongives
Answer» `1^(0)` AMINES `2^(0)` amines `3^(0)` amines all of these ANSWER :A

Discussion

27.	Ketonic form of acetone contains,
Answer» `8 - sigma " bond and " 2 - pi ` bonds `9-sigma " bonds and " 1 - pi` bond `7 - sigma" bonds and " 3 - pi` bonds `4- sigma " bonds and " 5-pi` bonds ANSWER :B

Discussion

28.	Isotonic solutions must have the same …………… .
Answer» solute density elevation in BOILING POINT depression in freezing point Solution :ISOTONIC solutions have same MOLAR CONCENTRATION and hence same elevation in boiling point and same depression in freezing point.

Discussion

29.	Isotonic solutions must have the same …….
Answer» Solute Density Elevation in boiling POINT DEPRESSION in FREEZING point Answer :C::D

Discussion

30.	Ketones react with X to give ketal X. is
Answer» glycerol. glycol. ethyl alcohol methanol. Answer :B

Discussion

31.	Isotonic solutions have
Answer» same BOILING POINT same VAPOUR pressure same MELTING point same OSMOTIC pressure. Answer :D

Discussion

32.	Isotonic solutions have :
Answer» same BOILING point same VAPOUR pressure same melting point same OSMOTIC pressure SOLUTION :Same osmotic pressure SOLUTIONS are called isotonic solutions.

Discussion

33.	Ketones react with Mg-HG over water gives
Answer» Pinacolone Pinacols Alcohols None of these Solution :Two molecules of ketones undergo reduction in the presence of `Mg//Hg` to form pinacol. `OVERSET(HOH)rarr underset(("pinacol"))underset(2,3-"dimethylbutane-2,3-diol")(CH_(3)-overset(" "CH_(3))overset(\|)underset(OH)underset(\|)(C)-overset(" "CH_(3))overset(\|)underset(OH)underset(\|)(C)-CH_(3)+Mg(OH)_(2))`

Discussion

34.	Ketones (R-overset(O)overset("\|\|")C-R') can be obtained in one step by(where R and R' are alkyl groups)
Answer» hydrolysis of ESTERS oxidation of primary ALCOHOLS oxidation of secondary alcohols reaction of ALKYL halides with alcohols. Answer :C

Discussion

35.	Isotonic solutions are those which have the:
Answer» Same OSMOTIC PRESSURE Same molarity Same density Same normality Answer :A

Discussion

36.	ketones [R-undersetOunderset"\|\|"C-R_1 , where R=R_1 = alkyl groups ] can be obtained in one step by
Answer» oxidation of primary alcohols hydrolysis of esters oxidation of TERTIARY alcohols reaction of acid HALIDES with alcohols Solution :By oxidation of tertiary ALCOHOL with stronger oxidising agents, ketones MAY be formed ALONG with carboxylic acid

Discussion

37.	Isotonic solutions are the solutions having the same
Answer» SURFACE tension vapour pressure osmotic pressure viscosity Answer :C

Discussion

38.	Ketones (R-underset(O)underset(\|\|)(C )-R_(1)) where R=R_(1)= alkyl group. It can be obtained in one step by
Answer» HYDROLYSIS of esters Oxidation of PRIMARY alcohol Oxidation of secondary alcohol Reaction of ACID HALIDE with alcohols Answer :C

Discussion

39.	Ketones R- overset(O) overset(\|\|)(C) - R' where R = R' alkyl group can be obtained in one step by
Answer» oxidation of `1^(@)` ALCOHOL HYDROLYSIS of ester hydrolysis of acid anhydride oxidation of `2^(@)` alcohol ANSWER :D

Discussion

40.	Isotonic solutions have same
Answer» DENSITY Molar CONCENTATION Normality None of these ANSWER :B

Discussion

41.	Ketones on reduction with ........... amalgam and water form pinacols.
Answer» SOLUTION :MAGNESIUM

Discussion

42.	Isotonic solutions.
Answer» SOLUTION :The SOLUTIONS having the same OSMOTIC pressure at a given temperatureare called ISOTONIC solution.

Discussion

43.	Ketones on reaction with NH_2CONHNH_2 form well defined crystalline compounds called:
Answer» Hydrazones Schiff's base Oximes Semicarbazones Answer :D

Discussion

44.	Isotonic solutions are solutions having the same
Answer» SURFACE tension Vapour pressure Osmotic pressure Viscosity Answer :C

Discussion

45.	Isothermally and reversibly, one mole of argon expands from 2 m^3 to 20 m^3 and produces 831.4 J of work. The temperature at which expansion takes place is __________ .(R=8.314 JK^-1 mol^-1)
Answer» 4342 K 43.42 K 434.2 K 316.42 K Answer :B

Discussion

46.	Isothermally at 27^(@) C, 1 mole of van der Waals gas expands reversibly from 2L to 20 L work done if a=1.42 xx 10^(12) dynes cm^(4)//"mole" and b=30 cc/mole
Answer» `5.677 XX 10^(3)` kJ `2.3 xx 10^(7)` kJ `9.2 xx 10^(3)` kJ `7.689 xx 10^(3)` kJ Answer :A

Discussion

47.	Ketones do not undergo oxidation easily due to _____.
Answer» SOLUTION :STRONG carbon-carbon BOND

Discussion

48.	Isothemal compresslbility (K) of a gas is defined as K=(1)/(V) ((dV)/(dP))_(nT). lsothermal compressibility of an ideal gas at 1.0 atmis:
Answer» `0.1" ATM"^(-1)` `0.01" atm"^(-1)` `1.0" atm"^(-1)` `0.01" atm"^(-1)` ANSWER :C

Discussion

49.	Ketones cannot be prepared in one step from
Answer» ALCOHOLS ALKENES ALKYNES ESTERS ANSWER :D

Discussion

50.	Isostructural group of molecules are
Answer» `NH_(3) , NF_(3) , BF_(3)` `NO_(3) , NO_(2) , SF_(4)` `XeO_(4), NH_(4)^(+) , CH_(4)` `CH_(3)^(-) , NH_(3) , NF_(3)` ANSWER :C::D

Discussion

Explore topic-wise InterviewSolutions in Current Affairs.

"Kg m"^(-1)s^(-2) is the unit of………………….. .

Isotropy.

KF has NaCl structure. What is the distance between K^(+) and F^(-) in KF, if its density is 2.48 g cm^(-3) ?

KF has NaCl structure. The edge length of its unit cell has been found to be 537.6 pm. The distance between K^(+) and F^(-) in KF is :

K_(f) for water is "1.86 K kg mol"^(-1). If your automobiles radiator holds 1.0 kg of water, how many grams of ethylene glycol (C_(2)H_(6)O_(2)) must you add to get the freezing point of the solution lowered to -2.8^(@)C?

Isotopes were discovered by

K_(f) for water is 1.86^(@)C*m^(-1). What is the molality of a solutionn which freezes at -0.192^(@)C? Assuming no change in the solute by raising the temperature, at what temperature will the solution boil ? (K_(b) for H_(2)O=0.515^(@)C*m^(-1))

Isotopes of same elemeents have the same number of

KF has ccp structure . Calculate the radius of unit cell if the side of the cube or edge length is 400 pm . How many F ions and octahedral voids are there in this unit cell ?

K_(f) for water is 1.86 K kg mol^(-1). If your automobile radiator holds 1.0 kg of water, how may grams of ethylene glycol (C_(2)H_(6)O_(2)) must you add to get the freezing point of the solution lowered to - 2.8^(@)C

K_(f) for water is 1.86 K kg "mol"^(-1). If your automobile radiator holds 1.0 kg of water, how many grams of ethylene glycol (C_(2)H_(6)O_(6)) must you add to get the freezing point of the solution lowered to - 2.8^(@)C ?

KF crystallizes in fce structure like sodium chloride. calculate the distance between K^(+) and F^(-) in KF. ("given : density of KF is 2.48 g cm"^(-3))

Isotope of which noble gas is isotonic (same number of neutrons) with Tritium?

K_f(+10)/K_tis known as :

Ketoximes are oxidised into 2^(@)-nitroalkane by using

Isotope of uranium used in atomic bomb is

Ketoxime on oxidation by trifluoroperoxy acetic acid gives

Isotonic solutions must have the same………..

Ketoximeon reductiongives

Ketonic form of acetone contains,

Isotonic solutions must have the same …………… .

Isotonic solutions must have the same …….

Ketones react with X to give ketal X. is

Isotonic solutions have

Isotonic solutions have :

Ketones react with Mg-HG over water gives

Ketones (R-overset(O)overset("||")C-R') can be obtained in one step by(where R and R' are alkyl groups)

Isotonic solutions are those which have the:

ketones [R-undersetOunderset"||"C-R_1 , where R=R_1 = alkyl groups ] can be obtained in one step by

Isotonic solutions are the solutions having the same

Ketones (R-underset(O)underset(||)(C )-R_(1)) where R=R_(1)= alkyl group. It can be obtained in one step by

Ketones R- overset(O) overset(||)(C) - R' where R = R' alkyl group can be obtained in one step by

Isotonic solutions have same

Ketones on reduction with ........... amalgam and water form pinacols.

Isotonic solutions.

Ketones on reaction with NH_2CONHNH_2 form well defined crystalline compounds called:

Isotonic solutions are solutions having the same

Isothermally and reversibly, one mole of argon expands from 2 m^3 to 20 m^3 and produces 831.4 J of work. The temperature at which expansion takes place is __________ .(R=8.314 JK^-1 mol^-1)

Isothermally at 27^(@) C, 1 mole of van der Waals gas expands reversibly from 2L to 20 L work done if a=1.42 xx 10^(12) dynes cm^(4)//"mole" and b=30 cc/mole

Ketones do not undergo oxidation easily due to _____.

Isothemal compresslbility (K) of a gas is defined as K=(1)/(V) ((dV)/(dP))_(nT). lsothermal compressibility of an ideal gas at 1.0 atmis:

Ketones cannot be prepared in one step from

Isostructural group of molecules are

K_(f) for water is 1.86^(@)Cm^(-1). What is the molality of a solutionn which freezes at -0.192^(@)C? Assuming no change in the solute by raising the temperature, at what temperature will the solution boil ? (K_(b) for H_(2)O=0.515^(@)Cm^(-1))