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85801.

Acetaldehyde on oxidation with SeO_2 gives :

Answer»

`CH_3COOH`
`C_2H_5OH`
`CHO.CHO`
None

Answer :C
Discussion
85802.

Acetaldehyde is used :

Answer»

In the PREPARATION of DYES
In the preparation of chloral
In the preparation of paraldehyde
All are CORRECT

ANSWER :D
Discussion
85803.

Acetaldehyde is

Answer»

OXIDISING agnet
REDUCING AGENT
both oxidising and reducing agent
NONE of these

Answer :C
Discussion
85804.

Acetaldehyde is the rearrangement product of:

Answer»

ETHYL alcohol
Vinyl alcohol
Allyl alcohol
Methyl alcohol

Answer :B
Discussion
85805.

Acetaldehyde is reduced with hydrogen in the presence of Nickel. What is the compound formed.

Answer»

ETHANOL
n-propanol
METHANOL
Isopropanol

Answer :A
Discussion
85806.

Acetaldehyde does not answer ..........

Answer»

LODOFORM TEST
LUCAS test
Benedict test
TOLLEN's REAGENT test

Solution :Lucas test
Discussion
85807.

Acetaldehyde cannot show

Answer»

IODOFORM test
Lucas test
Benedict's test
Tollen's test

Solution :`1^(@)` Primary alcohol `overset(ZnCI_(2)//HCI)rarr` White turbidity only heating
`2^(@)` Alcohol `overset(ZnCI_(2)//HCI)rarr` White turbidity after 5 min heating
`3^(@)` Alcohol `overset(ZnCI_(2)//HCI)rarr` easily in seconds
Discussion
85808.

Acetaldehyde cannot give

Answer»

IODOFORM test
LUCAS test
Benedict'stest
TOLLEN's test

Answer :B
Discussion
85809.

Acetaldehyde can not exhibit :

Answer»

Indoform TEST
BENEDICT's test
Tollen's test
Lucas test

ANSWER :D
Discussion
85810.

Acetaldehyde and Propyne can be distinguish by : (i) Tollen's reagent " " (ii) l_(2)//NaOH " " (iii) Lucas reagent " " (iv) neutral FeCl_(3)

Answer»

(i), (ii) & (III)
(ii) & (iii)
(i) & (ii)
(iii) & (IV)

Solution :Acetaldehyde and propyne can be DISTINGUISH by TOLLEN's reagent and Iodoform test.
Discussion
85811.

Acetaldehyde and benzaldehyde may be distinguished by reacting with

Answer»

DNP
`NH_(2)OH`
GRIGNARD reagent
Benedict's reagent

ANSWER :D
Discussion
85812.

Acetaldehyde and benzaldehyde can not be distinguished by

Answer»

TOLLEN's reagent
Fehling SOLUTION
Benediet solution
Iodoform test

Answer :A
Discussion
85813.

Acetaldehyde and benzaldehyde can be differentiated by :

Answer»

FEHLING test
Iodoform test
Tollen's reagent
both (a) and (B)

SOLUTION :
Discussion
85814.

Acetaldehyde and acetylene can be distinguished by :

Answer»

Tollen's reagent
Fehling solution
Lucas reagent
Iodoform test

Solution :Lucas reagent can not be USED to DISTINGUISHED ACETALDEHYDE and ACETYLENE.
Discussion
85815.

Acetaldehyde and acetone differ in their reaction with:

Answer»

`NaHSO_3`
`NH_3`
`PCl_5`
PHENYL hydrazine

Answer :B
Discussion
85816.

Acetaldehyde and acetone differ in their reaction with

Answer»

`NH_(3)`
Phenyl HYDRAZINE
`NaHSO_(3)`
`PCl_(5)`

Answer :A
Discussion
85817.

Acetaldehyde and acetone cannot be distinguished by

Answer»

Tollen's test
BENEDICT's test
LODOFORM test
Schiff's test

Answer :C
Discussion
85818.

Acetaldehyde and acetone can be identified by

Answer»

SCHIFF's reagent
2,4 -DNP test
Tollen's reagent
Lucas test

ANSWER :B
Discussion
85819.

Acetaldehyde andacetone can be identified by

Answer»

SCHIFF's TEST
LUCAS test
Iodoform test
Bromoform test

Solution :We know that, ALDEHYDE restores the colour of Schiff's reagent in the cold, while ketones do not give this test.
Discussion
85820.

Acetaldehyde.

Answer»

Solution :(1) Acetaldehyde is used as a starting material for the PREPARATION of MANY COMPOUNDS.
(2) It is used in the preparation acetic acdi and DDT and many haloform compounds.
Discussion
85821.

Acetaldehyde and acetone can be distinguished by

Answer»

MOLISCH test
Bromoform test
Solubility in water
Tollen's test

Solution :`CH_(3)CHO overset([AG(NH_(3))_(2)])rarrCH_(3)COOH+underset("Silver mirror RED")(Ag_(darr)+NH_(3))`
While acetone do not react.
Discussion
85822.

Acetaldebydc does not undergo Cannizzaro's reaction, Why?

Answer»

Solution :Acetaldehyde CONTAINS THREE `PROP`-hydrogen atom. Hence it does not answer Cannizzaro.s REACTION.
Discussion
85823.

Acetal or ketal is:

Answer»

VIC dialkoxy COMPOUND
`ALPHA , OMEGA` dialkoxy compound
`alpha`-alkoxy alcohol
Gem dialkoxy compound

Answer :D
Discussion
85824.

Acetal is produced by reacting an alcohol in the presence of dry HCl with

Answer»

acetaldehyde
ketone
ether
CARBOXYLIC ACID

ANSWER :A
Discussion
85825.

Acetal is obtained by reacting in the presence of dry HCI and alcohol with

Answer»

Aldehyde
Ketone
Ether
Carboxylic acid

Answer :A
Discussion
85826.

Acedified K_2Cr_2O_7 cannot oxidise

Answer»

Ferrous to FERRIC
Sulphide to sulphur
Stanous to stannic
FLOURIDE to FLOURINE

Answer :D
Discussion
85827.

Accurate determination of atomic masses is done with the instrument called is

Answer»

Spectrophotometer
MASS spectrometer
ATOMIC absorption spectrometer
Calorimeter

Solution :Atomic MASSES, DETERMINED by the mass spectrometer.
Discussion
85828.

Accumulation of lactic acid (HC_(3)H_(5)O_(3)), a monobasic acid in tissues leads to pain and a feeling of fatigue. In a 0.10 M aqueous solution, lactic acid is 3.7% dissociates. The value of dissociation constant Ka, for this acid will be

Answer»

`1.4 xx 10^(-5)`
`1.4 xx 10^(-4)`
`3.7 xx 10^(-4)`
`2.8 xx 10^(-4)`

Solution :`ALPHA = SQRT((K_(a))/(C))`
`alpha^(2) = (K_(a))/(C)` or `K_(a) = C alpha6(2)`
`K_(a) = 0.10 xx ((3.7)/(100))^(2)`
`K_(a) = 1.4 xx 10^(-4)`
Discussion
85829.

Accumulation of a substance at the surface is called sorption

Answer»

ABSORPTION
DESORPTION
ADSORPTION
none of these

Solution :adsorption
Discussion
85830.

Acctylenic hydrogens are acidic because

Answer»

Sigma electron density of C-H bond inacetylene is nearer to carbon, which has 50% s-character
Acetylene has only open hydrogen in each carbon
Acetylene contains least NUMBER of hydrogens among the possible hydrocarbons having two carbons
Acetylene belongs to the class of ALKYNES with molecular FORMULA, `C_(n)H_(2n-2)`

SOLUTION :The acidity of acetylene or 1-alkyne can be explained on the basis of molecular orbital concept according to which formation ofC-H bond in acetylene involves sp-hybridised carbon atom. Now since s electrons are closer to the nucleus than p electrons, the electrons present in a bond having more s character will be correspondingly more closer to the nucleus. Thus owing to high s character of the C-H bond in alkynes (s = 50%), the electrons constituting tllis bond are more strongly held by the carbon nucleus i.e., the acetylenic carbon atom or the :,p orbital acts as more electronegative species than the `sp^(2) and sp^(3)` with the result the hydrogen present on such a carbon atom `(-=C-H)` can be easily removed as a PROTON.
Discussion
85831.

Accroding to the kinetic theory of gases, for a diatomic molecule

Answer»

the PRESSURE exerted by the GAS is proportional to the mean VELOCITY of the molecules.
the pressure exerted by the gas is proportional to the root mean square velocity of the molecules
the root mean square velocity of the molecules is inversely proportional to the temperature
the mean translational kinetic energy of the molecules is proportioanl to the ABSOLUTE temperature

Answer :D
Discussion
85832.

Accroding to Markownikoff's rule, when hydrogen chloride adds to an unsymmetrical alkene, the hydrogen on HX attaches to

Answer»

CARBON at the end of the molecule
carbon in the middle of the molecule
carbon with more no. of hydrogens
carbon with least no. of hydrogens

Solution :We know that ACCRODING to Markowinkoff's RULE, carbon atom of the DOUBLE bond which contains least number of hydrogen atoms are most substiutedcarbon atoms. It measn hydrogen chloride adds to unsymmetrical alkene, the hydrogen of HALOGEN (HX) attaches to cabon with more number of hydrogens.
Discussion
85833.

Accroding to polarity, the expeceted reactivity of R-X is

Answer»

`R-Cl GT R-Br gt R-I`
`R-l gt R-I gt R-Br`
`R-I gt R-Br gt R-Cl`
`R-Br- gt R-I gt R-Cl`

ANSWER :A
Discussion
85834.

Accout for the following : (ii) Melting point of an acid with even number is higher than those of its neighbours with odd number of carbons atoms.

Answer»

SOLUTION :ACIDS with even NUMBER of carbon ATOMS fit into crystal lattice.
Discussion
85835.

Accout for the following : (i) Oxidation of toluence to C_(6)H_(5)CHO with CrO_(3) is carried out in presence of acetic anhydride.

Answer»

SOLUTION :It is used to PREVENT OXIDATION to benzoic ACID.
Discussion
85836.

Account for thhe folllowing (i) Cobalt (ii)is stablein aqueous solutionbut in the presenceof complexingreagentsit iseasilyoxidised. (ii)The d^(1) configurationis veryunstablein ions.

Answer»

SOLUTION :(i) Cobalt (iii)ion hasgreatertendencyto formcomplexesthancobalt(II) ion. ThereforeCo (ii)ion beingstablein aqueoussolutionchangesto Co (iii) ionin thepresenceof complexingreagentsand getoxidised .
(ii)Ionsof transitionmetalswith `d^(1)` configurationtendto loseone electronto ACQUIRE `d^(0)` configurationthat isquitestable . Thereforesuchions(with `d^(1)`)undergoeitheroxidationor disproportionation henceunstable .
Discussion
85837.

Account for the variation of atomic size along 3d-block elements.

Answer»

Solution :(i) As we MOVE from Sc (21) to Cr (24), atomic radius decreases because effective nuclear charge increases.
(ii) Atomic radius from Cr to Cu REMAINS ALMOST the same because the increase in the nuclear charge in COMPENSATED by the screening effect produced by 3d-electrons.
(III) Zinc has a completely filled d-subshell. Hence, atomic radius is larger than that of copper.
Discussion
85838.

Account for the statements : Arylhalides are extremely less reactive towards Nucelophilic substitution reactions .

Answer»

Solution :Aryl halides are extremely less reactive towards nucleophilic substitution reactions due to following REASONS .
`to` In aryl halides 'C' undergoes `SP^(2)` hybridised and it has greater S-character and ELECTRO negativity . So the C-X bond length is shorter .
`to ` In aryl halides resonance effect plays in an important role .
The ELECTRON pairs on halogen atom are in conjugation with `pi`-electrons of the ring.

In the above C - Br bond acquires apartial double bond nature due to resonance . This bond cleavage is difficult .
`to` The PHENYL cation formed in aryl halides is not stabilised by resonance .
Discussion
85839.

Account for the Some of the very old glass objects appear slightly milky instead of being transparent.

Answer»

Solution :When amorphous solids are heated and then cooled slowly, i.e., annealed they undergo crystallization at some temperature. GLASS objects recovered from ancient monuments LOOK MILKY because some crystallization has TAKEN place in them.
Discussion
85840.

Account for the statement : Noble gases have very low boiling points.

Answer»

Solution :Noble GASES have very low boiling points. This is due to the reason that the ATOMS of these elements are HELD together by weak VAN der WAALS forces (dispersion forces) of attraction both in the liquid as well as in the solid state.
Discussion
85841.

Account for the Silicon is an insulator but silicon doped with phosphorus acts as a semiconductor.

Answer»

Solution :Pure silicon has very few FREE ELECTRONS and has low conductivity and behaves almost as an insulator. Silicon doped with PHOSPHORUS has extra electrons and hence acts as semiconductor.
Discussion
85842.

Account for the malleability and ductility of metals on the basis of electron gas theory.

Answer»

Solution :When force (stress) is applied to a metal kernels (Positive ions or lattice POINTS) layers slide over one another. The SHAPE of the metal gets deformed.
Freely moving electrons also move around the deformed layers and the ENVIRONMENT around the metal ions remains unchanged.
OR
According to electron GAS theory, a metal CONTAINS an array of positively charged metal ions in a sea of mobile valence electrons and the bonding is non directional.
Discussion
85843.

Account for the following:Co(ll) is stable in aqueous solution but in the presence of strong ligand and air, itcan get oxidized to Colll). [Ni(CN)_(4)]^(2-), is square planar and diamagnetic whereas [NiCl_(4)]^(2-) is tetrahedral and paramagnetic

Answer»

Solution :CO(II) has the configuration `3d^(7)`, i.e. it has three unpaired electrons. Water being a weak ligand, the unpaired electrons do not pair up. In the presence of STRONG ligands and air, two unpaired electrons in 3d pair up and the third unpaired electron shifts to higher energy sub-shell from where it can be easily lost and hence shows an oxidation state of III.
(ii) `CN^(-)` a strong FIELD ligand forces the electrons to pair up in d-orbitals so it shows dsp hybridization DUE to which shape is square planar. Further no electron is left unpaired, so it is diamagnetic whileCl^(-) a weak_field ligand-eennot FORCE the electron to pair up showing `sp^(3)` hybridization. So, shape is tetrahedral and due to unpaired electron it is paramagnetic
Discussion
85844.

Account for the following : Zr and Hf exhibit similar properties.

Answer»

Solution :DUE to LANTHANIDE CONTRACTION the atomic RADIUS of Hf is almost equal to that of Zr. Hence these 4d and 5d - metals of GR. 4 show very similar properties.
Discussion
85845.

Account for the following : White phosphorus is more reactive than red phosphorus.

Answer»

SOLUTION :It is because WHITE PHOSPHORUS EXISTS as `P_4`whereas red phosphorus is polymeric.
Discussion
85846.

Account for the following: Trimethylamine is a weaker base than dimethylamie

Answer»

Solution :`- NH_2` attached to AROMATIC RING is HIGHLY ACTIVATING.
Discussion
85847.

Trimethylamine is less basic than dimethylamine.

Answer»

Solution :`- NH_2` ATTACHED to aromatic ring is HIGHLY ACTIVATING.
Discussion
85848.

Account for the following trends in atomic and ionic radii of transition metals. The atomic radii of the corresponding elements in '4d' series and 5d series are virtuallythe same.

Answer»

SOLUTION : It is a CONSEQUENCE of LANTHANOID contraction. This is because of the, filling of 4f orbitals before 5d.
Discussion
85849.

Account for the following: Atomic radius decreases from left to right in a period

Answer»

Solution :As the atomic nwnber increases, the newelectron enters an inner cZ-orbital and'the nuclear CHARGE increases by one unit 'The.shielding EFFECT of Selectrons is not very effective. ,So the. increased nuclear charge attracts the outer electrons more RESULTING in DECREASE in size (lanthanoid contraction).
Discussion
85850.

Account for the following trends in atomic and ionic radii of transition metals. The atomic radii of elements in 4d series are more than that of corresponding elements in 3d series.

Answer»

SOLUTION :This is because of ADDITION of ELECTRONS, to the ORBITALS ofihe outer shell in 4J series.Number of shell increases
Discussion