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84701.

Alkaline earth metals are:

Answer»

REDUCING agent
Oxidizing agent
Amphoteric
Acidic

Answer :A
Discussion
84702.

Alkaline earth metal salts are:

Answer»

Paramagnetic
Diamagnetic
Ferromagnetic
All of these

Answer :B
Discussion
84703.

Alkaline earth metal (s) which does (do) not impart colour to the flame is (are)

Answer»

Be
MG
Ca
Sr.

Solution :Be and Mg do not IMPART any colour to BUNSEN flame due to their high ionisation ENTHALPIES.
Discussion
84704.

Alkaline earth metal carbonates are decomposed on heating and produce residue. Thermal stability of reactant and residue will be - On moving down the group :-

Answer»

INCREASES and decreases respectively
Decreases and increases respectively
Increases and increases
Decreases and decreases

Solution :`MCO_(3) OVERSET(Delta)to MO+CO_(2)`
down the group, stability of carbonate `(uarr)`
stability of oxide `(DARR)`
Discussion
84705.

Alkaline earth metal compounds are less soluble in water than corresponding alkali metal compounds because former have:

Answer»

LOWER LATTICE energy
Higher I.P.
Higher COVALENT character
Lower covalent character

Answer :C
Discussion
84706.

Dilute aqueous KMnO_4 at room temperature reacts with RCH = CHR to give:

Answer»

RCHO
RCOOH
RCHOHCHOHR
`CO_2 + H_2O`

ANSWER :A
Discussion
84707.

Alkali metals posses metallic lustre when freshly cut because

Answer»

they have a hard surface and light is reflected back
their CRYSTAL structure contains ordered arrangement of constituent atoms
they contain loosely bound electrons which absor the photons and then re-emit
they are obtained from the MINERALS on which light has been falling for years

Solution :NAOH being DELIQUESCENT absord water from atmosphere therefore strength of solution will decrease.
Discussion
84708.

Alkali metals oxide are obtained by combustion of the metals.Although Na normally gives Na_2O_2,it will take up further oxygen at elevated pressure and temperature to form NaO_2.The per and superoxides of the heavier alkalies can also be prepared by passing stoichiometric amounts of oxygen into their solution in liquid ammonia. The different alkali metal oxides can be distinguished by reaction with water.The superoxides reacts with CO_2 and give oxygen gas.The stability of per and superoxides is based upon that larger cation can stablise larger anion, due to larger lattice energy. Alkali metals dissolve in liquid ammonia.Dilute solutions are dark blue in colour but as the concentration increases above 3M, the colour changes to copper bronze and the solution acquires the metallic lusture due to the formation of metal ions clusters.The solutions of alkali metals in liquid ammonia are good conductors of electricity due to the presence of ammoniated cations and ammoniated electrons.However, the conductivity decreases as the concentrations increases, since ammoniated electrons and ammoniated cation associate. On dissolving smaller (less than 3M) amount of sodium metal in liquid ammonia at low temperature , which one of the following does not occur ?

Answer»

Blue coloured solution is obtained
Ammoniated `Na^+` ion are formed in the solution
Liquid `NH_3` BECOMES good CONDUCTOR of ELECTRICITY
Liquid ammonia remains diamagnetic

Solution :Dilute solution of Na metal in liquid ammonia is deep blue coloured and highly conducting and paramagnetic in nature because of solvated cations and solvated ELECTRONS.
`M+(x+y)NH_3to[M (NH_3)_x]^(+) + [E (NH_3)_y]^(-)`
Discussion
84709.

Alkali metals oxide are obtained by combustion of the metals.Although Na normally gives Na_2O_2,it will take up further oxygen at elevated pressure and temperature to form NaO_2.The per and superoxides of the heavier alkalies can also be prepared by passing stoichiometric amounts of oxygen into their solution in liquid ammonia. The different alkali metal oxides can be distinguished by reaction with water.The superoxides reacts with CO_2 and give oxygen gas.The stability of per and superoxides is based upon that larger cation can stablise larger anion, due to larger lattice energy. Alkali metals dissolve in liquid ammonia.Dilute solutions are dark blue in colour but as the concentration increases above 3M, the colour changes to copper bronze and the solution acquires the metallic lusture due to the formation of metal ions clusters.The solutions of alkali metals in liquid ammonia are good conductors of electricity due to the presence of ammoniated cations and ammoniated electrons.However, the conductivity decreases as the concentrations increases, since ammoniated electrons and ammoniated cation associate. Solution of sodium metals in liquid ammonia is strongly reducing due to the presence of :

Answer»

SODIUM hydride
Sodium atoms
Sodium amide
Solvated ELECTRONS

Solution :Here solvated electrons ACTS as a REDUCING AGENT
Discussion
84710.

Alkali metals lose electrons in

Answer»

s-orbitals
p-orbitals
d-orbitals
f-orbitals

SOLUTION :Because their VALENCE ELECTRONS are PRESENT in s-orbitals
Discussion
84711.

Alkali metals have negative reduction potential and hence they behave as :

Answer»

OXIDISING agents
Lewis bases
reducing agents
electrolytes

Answer :C
Discussion
84712.

Alkali metals give colour in bunsen flame due to-

Answer»

LOW electronegativity
One `E^(-)` in OUTER most orbit
Smaller ATOMIC radii
Low IONISATION energy

Answer :D
Discussion
84713.

Alkali metals do not occur free in nature because:

Answer»

they are very reactive
they are volatile
their AMOUNT in EARTH's CRUST is very small
they are STRONG OXIDISING agents

Answer :A
Discussion
84714.

Alkali metals dissolve in liquid NH_(3) then which of the following observations is not true:

Answer»

It BECOMES paramagnetic
Solution TURNS into BLUE DUE to solvated electrons
It becomes diamagnetic
Solution becomes conducting

Answer :C
Discussion
84715.

Alkali metals are powerful reducing agents because:

Answer»

these are metals
their IONIC RADII are large
these are monovalent
their IONISATION POTENTIALS are low

Answer :D
Discussion
84716.

Alkali metals are good reducing agents because they easily:

Answer»

GAIN electrons
Lose electrons
Complete the octet
React with water

Answer :B
Discussion
84717.

Alkali metals are generally extracted by

Answer»

reduction METHODS.
displacement methods.
electrolytic methods.

Solution :ALKALI metals are highly electropositive and thus highly reducing .THEREFORE reduction, double decomposition and displacement methods for their EXTRACTION are not SUITABLE. Only electrolytic methods are useful for their extraction.
Discussion
84718.

Alkali metals are characterised by:

Answer»

GOOD CONDUCTOR of heat and electricity
High MELTING points
Low oxidation potentials
High ionisation enthalpies

Answer :A
Discussion
84719.

Alkali metal that reacts with nitrogen directly to form nitride is:

Answer»

Li
Na
K
Rb

Answer :A
Discussion
84720.

Alkali metal salt "X" gives a pale violet colour in flame test "X"is :

Answer»

NaCl
LiCl
KCl
None of these

Answer :C
Discussion
84721.

Alkali metal chloride soluble in pyridine is:

Answer»

LiCl
CsCI
NaCI
KCI

Answer :A
Discussion
84722.

Alkali metal chloride soluble in pyridine is

Answer»

NACL
KCL
CSCL
LiCl

Answer :D
Discussion
84723.

Affinity for hydrogen is maximum for

Answer»

`F_(2)`<BR>`Cl_(2)`
`Br_(2)`
I

Solution :BASED on ORDER of reactivity
Discussion
84724.

Affinity for hydrogen decreases in the group from fluorine to iodine. Which of the halogen acids should have highest bond dissociation enthalpy ?

Answer»

HF
HCL
HBr
HI

Solution :DUE to SMALL size of FLUORINE, H-F BOND is strong.
Discussion
84725.

Alizarin dye obtained from the root of madder plant is anthraquinone derivative. Its structure corresponds so

Answer»

1, 2-DIHYDROXY anthraquinone
2, 3-dihydroxy anthraquinone
1, 4-dihydroxy anthraquinone
1-hydroxy anthraquinone

Solution :ALIZARIN is 1,2 dihydroxy antraquinon i.e.,
Discussion
84726.

Alizarin belongs to the class of

Answer»

Vat dyes
Mordant dyes
Substantive dyes
Reactive dyes

Solution :A mordant is any substance which can be fixed to the fibre and which can be dyed later on. MOSTLY hydroxide or basic salts of chromium aluminium and iron are used as mordant. A dye which imparts different COLOURS in the presence of different mordant is REFERRED to as a mordant dye. For ex. alizarin is a mordant dye when mordanted with aluminium salt solution, it imparts ROSE red colour to FABRIC but the same fabric is dyed blue when it ismordanted the barium salt and it dyes violet when mordanted with Ferric salt.
Discussion
84727.

a)Express the relationship between the rate of production of water and the rate of disappearance of oxygen in the following reaction: 2H_(2) + O_(2) to 2H_(2)O b) For the chemical reaction X_(2)(g) + 2Y_(2)(g) to 2XY_(2)(g) Write the rate equation in terms of disappearance of Y_(2).

Answer»


SOLUTION :SELF EXPLANATORY
Discussion
84728.

Affinity for hydrogen decreases in the group from fluorine to iodine. Which of the halogen acids should have highest bond dissociation enthalpy?

Answer»

HF
HCL
HBR
HI

Solution :F being smallest has the shortest HF BOND and HENCE HF has the highest bond dissociation enthalpy.
Discussion
84729.

Alizarin a mordant is not used in

Answer»

Printing
COTTON DYEING
Painting
Chromium lakes for WOOD dyeing

Solution :It is the MORDANT so not USE in painting.
Discussion
84730.

Aliphatic nucleophilic substitution is mainly of two type S_(N^(1))" and "S_(N^(2)) . S_(N^(2)) reaction proceed with strong nucleophile in polar aprotic solvent. 3^(@) halides do not give S_(N^(2)) reaction. Inverted products are obtained in this reaction and mechanism of reaction occurs through the formation of transition state. S_(N^(1)) reaction proceed through the formation of carbocation in polar aprotic solvent. Solvent itself acts as nucleophile in this reaction. Racemization takes place in S_(N^(1)) reaction. Which one of the following will give S_(N^(2)) reaction?

Answer»

`H_(3)C-overset(CH_(3))overset(|)UNDERSET(CH_(3))underset(|)C-Cl`


`H_(2)C=CH-Cl`

Solution :N//A
Discussion
84731.

a.FeCI_(3) is yellow in aqueous solution but nopassing H_(2)S gas, solutionrurnsgreenExample. b.Aqueous solution of K_(2)Cr_(2)O, (orange) changes to yellow .can you explain? c. Potassium permanganate in purple in colour .On adding KOH, it turn gases, What is the compound formed? d. A metailic statue under scis-rain attack turns to blushing -green colour .What can be the probable metal and salt formed ? e. Oil painting turnblackish ater some time , What is the salt formed ? Assumeoil pointcontains Pb^(2+)

Answer»

Solution :a. `FaCI_(3)` is yellow in aqueoussolution , but on passing `H_(2)S` gas , solutionturns green , the due to formationof `FaCI_(2)` Which isgreen in colour .
`UNDERSET(Yellow)(FeCI_(3)) + H_(2) rarr underset(Green)(FeCI_(2)) + 2HCI + S`
b. Aqueous solution of potassium dicharomate `(K_(2)Cr_(2)O_(3))` changes to yellow due to
`underset("Orange")(Cr_(2)O_(7)^(2-))+2OH^(Theta) hArr underset(Yellow)(2CrO_(4)^(2-)) +H_(2)O`
c. Potassium permanganate `KMnO_(4)` reacts with `KOH` producingpotassiummanganate which is green in colour
`underset("Purple")(KMnO_(4)) + KOH rarr underset("Green")(2K_(2)MnO_(4)) + H_(2)O + (1)/(2) O_(2)`
d. Acid rain constitues `HNO_(2)` and `H_(2)SO_(4)`
`HNO_(3)` on reaction with copper present in state oxides metails `Cu` to `Cu^(2+)` , which give a blush-green colour to the state
`Cu_((s)) + HNO_(3(aq)) + 2H_((aq))^(Theta)rarr Cu_((aq))^(2+) 2NO_(2) + 2H_(2)O`.Hence metal is `Cu` and salt formed is `Cu^(2+)`
e. Oil paintingturnblackish after SOMETIMES , due toreaction of `Pb^(2+)` (present in oil points) with sulphides present is atmosphere , which result in the formation of `PbS` (black in colour)
`underset(("In oil paint"))(Pb^(2+)) + S^(2-) rarr underset(Black)(PbS darr)`
Discussion
84732.

Aliphatic nucleophilic substitution mainly takes place by two mechanisms (i.e) SN^1 & SN^2Primary halides mainly undergo by SN^2mechanism and are favourable in polar aprotic solvents. SN^1 reactions takes place mainly by tertiary halide and are more favourable in polar protic solvents, In case of tertiary halides, E_1comes competition to SN^1 reaction. Keeping in view of these general points, answer the following questionsWhich of the following reactions, the reactions takes place by SN^1mechanism mainly.

Answer»




`CH_3CH_2CH_2Br`

SOLUTION :FORMATION stable carbocation is the major REQUIRED condition, BENZYL carbocation is very stable dueto RESONANCE
Discussion
84733.

a.Explain the following a. Dipolemoment of CH_(3)F is 1.85D and that of CD_()F is 1.86D. b. 8- Hydroxy quinoline can be separarted from 4- hydroxy quinoline by steam disillation: c. The boiling point of (C_(2) H_(5))S gt (C_(2) H_(5))_(2)O. d. The pK_(a) of o- fluorobenzoic acid (I) is 4.14, wheraes that of p- chlorobenzicacid (II) is 3.99. e. Glycine exists as zwitterion , but PABA does not. f. Write teh structure of carbocationproduced on treatment of a compound (A) (Ph_(2) CHC(OH) Me_(2)) with SbF_(5)//SO_(2).

Answer»

<P>

Solution :It is DUE to the large size of `CD_(3)F`, but `D` is less `EN` than `H. (mu = q xx d)`.
b. It is due to intramolecular `H-` bonding in `8-` hydroxy-quinoline.

c. i. It is due to `H-` bonding in `CH_(3)OH`.
ii. In the absence of `H-` bonding high MOLECULAR mass of `C_(2)H_(5))_(2)S` has higher point than `(C_(2) H_(5))_(2)O`.

the aliphatic`(-NH_(2))` group is sufficiencty basic to accept`H^(o+)` from `(-COOH)` and exists as a dipolar ion (zwitterion), wheras in `PABA` (`p-` aminobenzoic acid,) an aromatic acid, `(-COOH)` is not strong enough to DONATE `H^(o+)` to a MUCH weaker base `(Ar-NH_(2))`. So the dipolar ion is not fomed.
f.
It is formed by propronation and susequent elimination of `H_(2)O`, followed by `H^(o-)` ion transfer to from a more stable carbonium ion.
Discussion
84734.

Aliphatic nucleophilic substitution mainly takes place by two mechanisms (i.e) SN^1 & SN^2Primary halides mainly undergo by SN^2mechanism and are favourable in polar aprotic solvents. SN^1 reactions takes place mainly by tertiary halide and are more favourable in polar protic solvents, In case of tertiary halides, E_1comes competition to SN^1 reaction. Keeping in view of these general points, answer the following questions(+)C_6H_5CH(CH_3)Cl to (pm) C_6H_5CH(OH)CH_3in which of the following solvents, the above reaction is most favourable

Answer»

75% WATER + 25% `CH_3OH`
25% water + 75% methanol
100% methanol
10% water + 90% methanol

Solution :Given reaction follows `SN^1` mechanism, which TAKES PLACE favorable in polar solvents due to FORMATION of cation is the intermediate step
Discussion
84735.

(a)Explain Mendius reduction with an equation. (b) When aniline is treated with HNO_(2) at 273-278 K, benzene diazoniuin chloride is formed. Write the equation and name the reaction. (c) What is Hinsberg’s reagent?

Answer»

Solution :(a) Reduction of nitriles by sodium in alcohol to GET a primary AMINE is called Mendius reduction.
` R - CN + 4(H) overset("Nainalcohal")(to)R-CH_(2)-NH_(2)`
(b) `C_(6)H_(5)-NH_(2) + NaNO_(2) + 2HCl to C_(6)H_(5)N_(2)Cl + NaCl + H_(2)O`
The name of the reaction is Diazotisation
(c) Benzene sulphonyl chloride [OR] `C_(6)H_(5)SO_(2)CI`
Discussion
84736.

Aliphatic nucleophilic substitution is mainly of two type S_(N^(1))" and "S_(N^(2)) . S_(N^(2)) reaction proceed with strong nucleophile in polar aprotic solvent. 3^(@) halides do not give S_(N^(2)) reaction. Inverted products are obtained in this reaction and mechanism of reaction occurs through the formation of transition state. S_(N^(1)) reaction proceed through the formation of carbocation in polar aprotic solvent. Solvent itself acts as nucleophile in this reaction. Racemization takes place in S_(N^(1)) reaction. Which one of the following will give racemised product in C_(2)H_(5)OH?

Answer»

`H_(3)C-underset(CH_(3))underset(|)(CH)-BR`
`Ph-OVERSET(CH_(3))overset(|)underset(CH_(3))underset(|)C-Cl`
`Ph-overset(CH_(3))overset(|)underset(H)underset(|)C-Cl`

Solution :N//A
Discussion
84737.

Aerosols present in atmospheric air may be :

Answer»

POSITIVELY charged
Negatively charged
Neutral
Conmination of all (a),(B) and ( C )

ANSWER :D
Discussion
84738.

Aliphatic nucleophilic substitution is mainly of two type S_(N^(1))" and "S_(N^(2)) . S_(N^(2)) reaction proceed with strong nucleophile in polar aprotic solvent. 3^(@) halides do not give S_(N^(2)) reaction. Inverted products are obtained in this reaction and mechanism of reaction occurs through the formation of transition state. S_(N^(1)) reaction proceed through the formation of carbocation in polar aprotic solvent. Solvent itself acts as nucleophile in this reaction. Racemization takes place in S_(N^(1)) reaction. Which of the following compounds will give S_(N^(1)) reaction ?

Answer»

`Ph-OVERSET(CH_(3))overset(|)underset(Cl)underset(|)C-CH_(2)CH_(3)`
`H_(3)C-Cl`
`H_(3)C-CH_(2)-Br`

SOLUTION :N//A
Discussion
84739.

Aerosols:

Answer»

LIQUID in SOLID
Liquid in gas
Gas in liquid
Solid in liquid.

Answer :B
Discussion
84740.

Aliphatic ethers are purified by shaking them with a solution of ferrous salt to remove______which are formed on prolonged standing in contact with air.

Answer»

SOLUTION :PEROXIDES.
Discussion
84741.

Aerobic oxidation is caused by :

Answer»

Aerobic BACTERIAS in PRESENCE of EXCESS of oxygen
Anaerobic bacerias in presence of insufficient oxygen
Aerobic bacterias in the absence of oxygen
Both anaerobic and aeronbic bacterias in any condition

Answer :A
Discussion
84742.

(A)Enthalpy of physical adsorption is lower than chemical adsorption (R ) Molecules of adsorbate and adsorbent are held together by vanderwall forces in physical adsorption and by chemical bonds in chemical adsorption

Answer»

Both (A) and (R ) are true and (R ) is the correct EXPLANATION of (A)
Both (A)and (R ) are true and (R ) is not the correct explanation of (A)
(A) is true but (R ) is false
Both (A) and (R ) are false

ANSWER :A
Discussion
84743.

Aliphaticdiazoniumcholdridean decompositiongives

Answer»

`1^(0)`- amine
alchols
ALDEHYDES
alkanes

ANSWER :B
Discussion
84744.

Aerated drinks is an example of

Answer»

liquid in liquid
GAS in liquid
solid in liquid
liquid in gas.

Solution :Aerated DRINKS is an EXAMPLE of gas in liquid.
Discussion
84745.

Aliphatic carboxylic acids shows isomer of type,

Answer»

POSITION
CHAIN
FUNCTIONAL
all of these

Answer :B
Discussion
84746.

Adsorptionsof gas follows Freundich adsorption isotherm . X is the mass of the gas adsorbed on mass m of the adsorbent. The plot oflog"" (x)/(m)versuslogp is log""( x)/(m)shown in the givengraph(x)/(m)is propotional to:

Answer»

<P>` P^(6)`
`P^(6//5)`
` P^(5)`
` P^(5//6)`

ANSWER :B
Discussion
84747.

Aliphatic amines are stronger bases than ammonia due to _______ of alkyl groups.

Answer»


ANSWER :`+I` GROUPS
Discussion
84748.

Adsorption theory is applicable for

Answer»

HOMOGENEOUS CATALYSIS
heterogeneous catalysis
autocatalysis
induced catalysis.

Answer :B
Discussion
84749.

Aliphatic amines are soluble in water because :

Answer»

They are basic
They are amino COMPOUNDS
They are lighter than WATER
Of formation of hydrogen BONDS with water

ANSWER :D
Discussion
84750.

What is heterogeneous catalysis ? What role does adsorption play in heterogeneous catalysis ?

Answer»
Discussion