Explore topic-wise InterviewSolutions in Current Affairs.

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.

Lines of Balmer series appear in ________ region.

Answer»

SOLUTION :VISIBLE
Discussion
2.

Linear form of carbon dioxide molecule has two polar bonds. Yet the molecule has zero dipole moment. Why?

Answer»

Solution :(i) The linear form of carbon DIOXIDE has zero DIPOLE moment, even though it has two polar bonds.
(ii) In `CO_2` there are two polar bonds [C =O], which have dipole moments that are equal in magnitude but have opposite direction
(III) Hence the NET dipole moment of the `CO_(2)` is `MU= mu_1 + mu_2 = mu_1+(-mu_1)=0`
(iv) `overset(O=)underset(mu_1)rarr overset(C)("") overset(=O)underset(mu_1)larr`
(v)In this case, `mu=vecmu_1 + vec mu_2 = vecmu_1 + (-vecmu_1)=0`
Discussion
3.

Linear polyenes on ozonoysis give two moles of acetaldehyde and one mole of propandial.Linear polyene will be

Answer»

Alkadiene
Allkatriene
Alkatetraene
Alkapentaene

Solution :Polyene is alkadiene
`R- CH = CH_2 - CH = CH - R to R - CHO + OHC - CH_2 - CHO + RCHO`
Discussion
4.

Linear form of carbondioxide molecule has two polar bonds. Yet the molecule has zero dipole momentwhy?

Answer»

Solution :(i) The linear form of carbon dioxide has zero dinole moment, even thougn it has two polar bonds.
(ii) In `CO_(2),`there are two polar bonds [C = O] which have dipole momens that are equal in magnitude but have OPPOSITE direction.
(iii) HENCE the net dipole moment of the `CO_(2) " " is " "mu = mu_(1)+ (-mu_(1))=0`
(iv)
(v) In this case,
(iv) `underset(mu_(1))overset(O=)RARROVERSET(C=O)underset(mu_(1))LARR`
(v) In this case. `mu=vecmu_(1)+vecmu_(2)=vecmu_(1)+(-VEC(mu_(1)))=0`
Discussion
5.

Line spectrum is characteristic of

Answer»

Atoms
Molecules
Any SUBSTANCE in SOLID STATE
Any substance in LIQUID state

Answer :A
Discussion
6.

Lindlar's catalyst cannot be used to carry out the following process A) CH_(3)-C-=C-CH_(3)overset(H_2)rarrtrans Butene-2 B) CH_(3) -C-=C-CH_(3) overset(H_2)rarr Butane C) C_3H_2overset(H_2)rarrC_2H_6 D) CH_3-C-= CH_(3) overset(H_2)rarrcis Butene - 2

Answer»

A only
A, B and D only
A, B and C only
A, C and D only

ANSWER :C
Discussion
7.

Lindlar's catalyst is

Answer»

PT in ethanol
`PD + BaSO_4 `
Ni in ethanol
NA in LIQ. `NH_3 `

Solution :Pd + `BaSO_4`
Discussion
8.

Limiting line of any spectral series in the hydrogen spectrum is the line when n_(2) in the Rydberg's formula is .........

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SOLUTION :INFINITY
Discussion
9.

Limited amount of Grignard's reagent and ethyl acetate reacts to give

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Acid
Ketone
Aldehyde
Alcohol

Solution :`H_(3)C - overset(O)overset(||)(C) - OC_(2)H_(5) + H_(3) overset(-)(C) overset(+)(M) gI overset("dry ether")RARR H_(3) C - UNDERSET(CH_(3))underset(|)overset(OMgI)overset(|)(C) - OC_(2)H_(5) underset(underset(-Mg(OH)I)(-C_(2)H_(5)OH))overset(H_(2)O // H^(+))rarr`
`H_(3)C - underset(CH_(3))underset(|)overset(O - H) overset(|)(C) - O - H overset(-H_(2)O)rarr underset("Acetone")(H_(3)C - overset(O)overset(||)(C) - CH_(3))`
Discussion
10.

Limiting compositions of f-block hydrides are

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`MH_(2)&MH_(3)`
`MH_(3)&MH_(5)`
`MH_(2)&MH_(8)`
`MH_(2)&MH_(6)`

ANSWER :A
Discussion
11.

Lime water turning milky is due to the formation of ______________

Answer»

CALCIUM carbonate
calcium hydroxide
Calcium oxide
Calcium chloride

Answer :A
Discussion
12.

Lime water in aqueous solution gives white precipitate by passing carbondioxide, but the precipatate dissolves in excess carbondioxide. Why?

Answer»

Solution :Lime water gives insoluble calcium carbonate with CARBONDIOXIDE
`Ca(OH)_(2)+CO_(2)rarrCaCO_(3)darr+H_(2)O`
Calcium carbonate is soluble in water in the PRESENCE of carbondioxide, GIVING calcium bicarbonate
`CaCO_(3)+H_(2)O+CO_(2)rarrCa(HCO_(3))_(2)`
Discussion
13.

Lime stone is heated at elevated temperature ........ furnace to convert it in quick lime.

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Rotary
Reverberatory
Blast
All

Solution :`CaCO_(3) OVERSET(Delta)hArr CaO+CO_(2(G))`
Discussion
14.

Mortar is a mixture of

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I part of SLAKED lime, 1 part of sand and WATER
1 part of slaked lime, 3 part of sand and water
3 parts of slaked lime, 3 parts of sand and water
3 parts of slaked lime, 1 part of sane and water

Solution :Lime MORTAR is prepared by mixing of 1 part of slaked lime and 3 parts of sand and water.
Discussion
15.

Like COwhy its analog of SiOis notstable.

Answer»

Solution :CO isresonance hybridof the following two structure :

Thus, CO contains`ppi-ppi`multiplebonds. This is DUE to the reason that carbonhas a STRONG tendency to FORM `ppi-ppi`multiplebonds due toits smallsize and highelectronegativity. Silicon, on theother hand , because of itsbigger size andlowerelectronetivityhas not tendency to form `ppi- ppi` multiple bonds andhence Si does not form`SIO` molecule analogousto `CO`molecule.
Discussion
16.

Like aluminum Beryllium is inert towards ...... acid.

Answer»

HCl
`H_(2)SO_(4)`
`HNO_(3)`
`CH_(3)COOH`

Answer :C
Discussion
17.

Like alkali metals, alkaline earth metals are also soluble in .......

Answer»

Ether
Ammonia
Alcohol
Water

Answer :B
Discussion
18.

Like Al_(4)C_(3), Be_(2)C is produce ….. gas.

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Oxygen
Hydrogen
Ethane
Methane

Answer :D
Discussion
19.

LiHCO_(3) and Ca(HCO_(3))_(2) are not found in solid state .

Answer»


SOLUTION :They are HIGHLY SOLUBLE in WATER
Discussion
20.

LiH is an example of _______________ hydride.

Answer»

ionic
saline
covalent
both a and b

Answer :D
Discussion
21.

Light waves travel with the speed of 3 xx 10^(8) "m s"^(-1). Express the speed in miles are per hour.

Answer»


Solution :`1.6 xx 10^(3)m=1" MILE" :. "conversion factor"=(("1 mol"))/((1.6xx10^(3)m))`
`3.6 xx 10^(3)s=1HR:. "conversion factor"=((1hr))/((3.6xx10^(3)s))`
`(3xx10^(8)m)/(1s)=((3xx10^(8)m)xx("conversion factor"))/(1sxx("conversion factor"))`
`=(3xx10^(8)m)xx(("1 mile"))/((1.6xx10^(3)m))xx(1)/((1s))xx((3.6xx10^(3)s))/((1hr))=6.75xx10^(8) "miles/hr"`.
Discussion
22.

Light of wavelength 4000 Å falls on the surface of cesium. Calculate the energy of the photoelectron emitted. The critical wavelength for photoelectric effect in cesium is 6600 Å.

Answer»

SOLUTION :`1.95 XX 10^(-19)` JOULE
Discussion
23.

Light scattering takes place in

Answer»

SOLUTIONS of electrolyte
Colloidal solution
Electrodialysis
Electroplating

Answer :B
Discussion
24.

Lifetimesof themoleculesin theexcitedstatesare oftenmeasuredby usingpulsedradiationsourceof durationnearlyin the nanosecondrange. If theradiationsourcehas theemittedduringthe pulsesourceis 2.5 xx 10^(15).Calculatethe energyof the source .

Answer»

Solution :radiationduration`=2 ns = 2 xx 10^(9) s`
Frequency= `(1) /(" radiation period") = (1)/( 2xx 10^(9) s)`
total= NOOF photon(N ) `xx ` energyof 1photon(hv )E = Nhv
`=(2.5 xx 10^(15) )(1.626 xx 10^(34) J s) (5.0 xx 10^(8) s)`
`=82 .825 xx 10^(11) J`
`=8.282xx 10^(10)J`
Discussion
25.

LiF is..........in water due to its high.........energy.

Answer»

SOLUTION :INSOLUBLE, LATTICE
Discussion
26.

LiF is less soluble in water than KF because

Answer»

LIF more is covalent than KF
LiF has higher LATTICE ENERGY than KF
LiF has higher enthalpy of hydration than KF
Li+ ions are not extensively HYDRATED than `K^(+)` ions

Solution :Conceptual
Discussion
27.

LiF is ionic but BeF_2 is covalent. Comment.

Answer»

Solution :The electronegativity difference between elements of LiF is 3 and of `BeF_(2)` is 2.5. Both are expected to be ionic. But DUE to high POLARISATION ABILITY of `Be^(2+)` ion, `BeF_(2)` is not pure ionic. It is more covalent.
Discussion
28.

Liebig test is used ot estimate

Answer»

H
C
C and H both
N

Answer :C
Discussion
29.

LiCl is soluble in water whereas LiBrand Lil are soluble in organic solvent. Give reason

Answer»

SOLUTION :LITHIUM chloride (LiCl) is ionic in nature and it is soluble in POLAR solvent water, whereas lithium bromide and lithium IODIDE are covalent and are soluble in non-polar ORGANIC solvents
Discussion
30.

LICIO_(4) is more soluble than NaCIO_(4)Why?

Answer»

SOLUTION :The small size of the Lition MEANS that it has a very high enthalpy of hydration and so lithium salts are MUCH more soluble than the salts of other GROUP 1. E.g. `LiClO_(4)`, is upto 12 TIMES more soluble than `NaClO_(4)`
Discussion
31.

Liberation of dihydrogen from methane by steam reaction ?

Answer»

Solution :METHANE reacts with steam at 1273 K in the PRESENCE of nickel catalyt to form carbon monoxide and dihydrogen. This method is used for industrial preparation of dihydrogen gas.
`UNDERSET("Methane")(CH_(4(g)))+underset("Steam")(H_(2)O_((g))) underset(1273 K)overset(Ni)rarr underset("monoxide")underset("Carbon")(CO_((g))) + underset("Dihydrogen")(3H_(2(g)))`
Discussion
32.

LiAlH_(4)is used as ______.

Answer»

anoxidisingagent
areducingagent
a MODERATOR
a watersoftener

ANSWER :B
Discussion
33.

LiA//H_4 is used as :

Answer»

an OXIDANT
a REDUCTANT
a mordant
water softner

Solution :(B) It is a FACT
Discussion
34.

Li_2CO_3 decomposes readily whereas other carbonates are not. Why?

Answer»

Solution :The carbonates `(M_2 CO_3)` of ALKALI metals are REMARKABLY more stable UPTO 1270 K above which they first melt and then decompose to FORM their oxides, whereas `Li_2 CO_3` is less stable and decomposes readily .
`Li_2 CO_3 + Delta to Li_2 O + CO_2 uarr`
This is DUE to the large size differnece between `Li^+` and `CO_3^(2-)` which makes the crystal lattice unstable.
Discussion
35.

Li_(2)SO_(4) is not isomorphous with sodium sulphate

Answer»

Due to SMALL size of lithium
Due to high COORDINATION number of lithiu
Due to high ionisation energy of lithium
Both (B) and (c)

SOLUTION :Due to small size of lithium `Li_(2)SO_(4)` is ot ISOMORPHOUS with `Na_(2)SO_(4)`
Discussion
36.

Li_(2)CO_(3) decomposes readily whereas other carbonates are not. Why?

Answer»

Solution :The carbonates `(M_(2)CO_(3))` of alkali METALS are remarkably more stable upto 1270K above which they FIRST melt and then decompose to FORM their oxides, whereas `Li_(2)CO_(3)` is less stable and decomposes readily
`Li_(2)CO_(3) + /_\ to Li_(2)O + CO_(2)uarr`
This is due to the large size difference between `Li^(+)` and `Co_(3)^(2-)` which makes the crystal LATTICE unstable
Discussion
37.

Li on reaction with nitrogen form which type of compound?

Answer»

Lithium-nitrite
Lithium-nitrate
Lithium - nitride
None of above

Answer :C
Discussion
38.

Li, Na, K are Dobereiner triads. If the atomic weight are 7 and 39 respectively then what would be the atomic weight of Na ?

Answer»

Solution :Li (Lithium) = 7 atomic number
K (Potassium) = 39 atomic number
MIDDLE element of triads is NA
` :. ` Atomic weight of sodium = `((Li +K))/2= (7 + 39)/2 = 46/2 = 23`
Discussion
39.

Li , Na and K react withdioxygen giving ……… , ………and …………respectively .

Answer»

SOLUTION :`Li_(2)O , Na_(2)O_(2) , KO_(2)`
Discussion
40.

Li is not used in ......

Answer»

AERO PLANE industries.
nuclear reactor.
alloy formation.
as REDUCING agent.

Answer :B
Discussion
41.

Li - Mg alloy used to prepare ......

Answer»

SOLUTION :ARMOUR PLATES
Discussion
42.

Li+have high hydration fraction and therefore its salts are usually hydrated in nature.

Answer»

SOLUTION :TRUE STATEMENT
Discussion
43.

Li is less vigorously react then Na, because its...

Answer»

SMALLER SIZE and HIGH HYDRATION enthalpy.
Larger size and high IONIZATION enthalpy.
High electronegativity.
Larger size and high hydration enthalpy.

Answer :A
Discussion
44.

Li has the following abnormal behaviour in its grou

Answer»

Lithium CARBONATE decomposes into its oxide on heating unlike other element
LiCl is covalent in nature
Li3N is a STABLE compound
LiCl is a poor CONDUCTOR of electricity in molten state

Solution :Due to SMALL SIZE and high charge / radius ratio
Discussion
45.

PCl_(5) +SO_(2) rarr A+B A overset(3H_(2)O)rarrHCl C overset("Red hot")rarrD +H_(2)O Compound 'A' is

Answer»

0
1
-2
`-1

Solution :
Discussion
46.

Li (520), Be (899) and C (1086) kJ "mol"^(-1) ionisation enthalpy then B contain which are ionisation enthalpy 800 or 900 kJ/mol why ?

Answer»

Solution :`800 KJ" mol"^(-1)` because order of IONISATION ENTHALPY in second period is `Li lt B lt Be lt C`.
Discussion
47.

Lewis symbol for second period

Answer»

SOLUTION :
Discussion
48.

Lewis acids among the following are a) CCl_(4) b) SiCl_(4) c) GeF_(4)

Answer»

only a and B
only b and c
only a and c
a, b and c

Answer :B
Discussion
49.

Let vartheta_(1) be the frequency of the series limit of the Lyman series and vartheta_(2) be the frequency of the first line of the Lyman series and vartheta_(3) be the frequency of the series limit of Balmar series, then

Answer»

`v_1 -v_2 = v_3`
`v_2 - v_1 = v_3`
`v_3 -1/2 (v_1 +v_2)`
`v_1 + v_2 = v_3`

Solution :`bar(upsilon)=1/(LAMBDA) = R(1)/(n_1^2) - 1/(n_2^2) , upsilon_1 = CR,`
`upsilon_2 = (3cR)/(4) , upsilon_3 = (cR)/(4) THEREFORE upsilon_1 - upsilon_2 = upsilon_3`
Discussion
50.

Let u_(av), u_(rms)and u_(mp)are average, root means square and most probable speed the molcules in an ideal monoatomic gas at absolute temperature T. The mass of molecule is m, then :

Answer»

none of the moelcules can have a speed greater than `sqrt(2)u_(rms)`
none of the molecules can have a speed less than `sqrt(2)u_(MP)`. 
`u_(av) lt u_(rms) lt u_(mp)`
the AVERAGE kinetic energy of molecule is `3/4m u_(mp)^2`

SOLUTION :`K.E. = 1/2 mU_(rms)^2 = 1/2 m xx 3/2 xx U_(mp)^2 = 3/4 U_(mp)^2`.
Discussion