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7901.

What is corrosion of metal ? Give its characterization and damage.

Answer»

Solution :* Corrosion slowly coats the surfaces of metallic objects with oxides or other salt of the metal, which is known as corrosion of metal. In corrosion, a metal is oxidised by loss of electrons to OXYGEN and formation of oxides.
* Characterization of metal corrosion : (i) The rusting of iron, (ii) TARNISHING of silver, (iii) development of GREEN coating on copper and bronze etc.
* Damage due to corrosion : We lose crores of rupees every year on ACCOUNT of corrosion. It CAUSES enormous damage of buildings, bridges, ships and to all objects made of metals especially that of iron.
Discussion
7902.

Which of the following add nutritive value to food?

Answer»

Sweeteners
Antioxidants
Fat emulsifiers
None of these

Solution :NEITHER any of the substances among GIVEN options POSSESS nutritive value.
Discussion
7903.

Which of the following is an example of adsorption ?

Answer»

Water on silica gel
WATE on CALCIUM chloride
hydrogen on finely divided nickel
Oxygen on METAL surface

Answer :B
Discussion
7904.

Which of the following mixture gives chromic

Answer»

`K_(2)Cr_(2)O_(7)" and conc." H_(2)SO_(4)`
`K_(2)_Cr_(2)O_(7) and HCL`
`K_(2)SO_(4) and conc. H_(2)SO_(4)`
`H_(2)SO_(4) and HCl`

Solution :MIXUTURE of `K_(2)Cr_(2)O_(7) and "conc," H_(2)SO_(4)` is known as CHROMIC acid.
Discussion
7905.

Which of the following weighs the maximum ?

Answer»

2.24 L of `CO_2`at N.T.P.
`6.02 XX 10^23`MOLECULES of `CO_2 `
`6.02 xx 10^23`ATOMS of carbon
10 G of carbon

Solution :`6.02 xx 10^23`molecules of `CO_2 `
Discussion
7906.

Which of following element produces oxide with conc. HNO_(3)

Answer»

N
P
As
Sb

Answer :D
Discussion
7907.

Which of the following is a protein

Answer»

serine
glycogen
alanine
keratin

Answer :D
Discussion
7908.

Using IUPAC norms write the formulas for the following: Pentaamminenitrito-N-cobalt(III)

Answer»

SOLUTION :`[CO(NH_(3))_(5)(NO_(2))]^(2+)`
Discussion
7909.

Which of the followig reaction is possible at anode:-

Answer»

`2Cr^(3+)+7H_(2)OtoCr_(2)O_(7)^(2-)+14H^(+)`
`F_(2)to2F^(-)`
`(1)/(2)O_(2)+2H^(+)toH_(2)O`
None of these

Solution :Oxidation ALWAYS occurs at anode.
Discussion
7910.

What are leaching process?

Answer»

Solution :This method is based on the SOLUBILITY of the ore in a suitable SOLVENT and the reactions in aqueous solution. In this method, the crushed ore is allowed to dissolve in a suitable solvent, the metal present in the ore is converted to its SOLUBLE salt or complex while the gangue remains insoluble. This process is also CALLED chemical method.
Discussion
7911.

Which of the following on heating with aqeous KOH produces acetaldehyde?

Answer»

`CH_(3)COCL`
`CH_(3)CH_(2)Cl`
`CH_(2)ClCH_(2)Cl`
`CH_(3)CHCl_(2)`.

Solution :`CH_(3)CHCl_(2)` (a GEMINAL DIHALIDE) forms ACETALDEHYDE on reacting with aqueous (KOH)
.
Discussion
7912.

Which of the followingstatements are incorrect-

Answer»

heat of hydrogenation of `CH_(3)CH_(2)CH=CH_(2)` is less than that of `(CH_(3))_(2)C=CH`
`overset(Theta)(C)CI_(3)` is more stable than`overset(Theta)( C) F_(3)`
BOND lenghts of three carbon - oxygen bonds in carbonate`(CO(2^(-))/(3))` ion are not EQUAL
free radicals are paramagnetic

Answer :A::C
Discussion
7913.

Which of the following statements are incorrect-

Answer»

sodium extract is FIRST boiled with dilure HCI during detection ofhalogens by Lassaigne's test
if in an organic compound, both nitrogen and sulphur are present, then blood - red colouration is OBSERVED during detection of nitrogen by Lassaigne's test
organic COMPOUNDS which dissociate at their melting points are purified by VACUUM disillation
in paper CHROMATOGRAPHY, the stationary phase is solid while the mobile phase is liquid

Answer :A::D
Discussion
7914.

Thermal decomposition of zinc nitrate give:

Answer»

`Zn`
`ZNO`
`Zn(NO_(3))_(2)`
`NO`

Answer :B
Discussion
7915.

What are (i) Brownian movement and (ii) Tyndall effect ? Draw diagrams to illustrate them.

Answer»

SOLUTION :(i) Brownian movement: It is zig-zag motion in colloidal PARTICLES. It is due to collision between particles of dispersed PHASE among themselves as well as with particles of dispersion medium.
(ii) Tyndall effect : When beam of light is passed through colloidal particles, its path BECOMES clearly visible. It is CALLED Tyndall effect. It is due to scattering of light of by colloidal particles.
Discussion
7916.

Which of the following is not characteristic of amines :

Answer»

They smell LIKE ammonia
They are INFLAMMABLE in air
They show the property of HYDROGEN bonding
They are amphoteric in nature .

Answer :D
Discussion
7917.

The standard reduction potentials of A^(+)//A, B^(+)//B and C^(+)//C are +3.03 V , -0.70 V and -0.42 V respectively. Which of the following reactions is spontaneous ?

Answer»

`A^(+)+B to A+B^(+)`
`C^(+)+A to C+A^(+)`
`B^(+) +A to B+A^(+)`
`B+C to B+C^(+)`

ANSWER :A
Discussion
7918.

Which of the following reactions goes almost all the way to completion, and which proceeds hardly at all ? N_(2)(g) + O_(2)(g)hArr2NO (g), K_(c) = 2.7 x× 10^(-18)

Answer»


ANSWER :INCOMPLETE
Discussion
7919.

The standard reduction potential at 298K for the following half reaction are given against each Zn^(2+)(aq)+2e^(-)hArrZn(s)""-0.762 Cr^(3+)(aq)+2e^(-)hArrCr(s)""-0.740 2H^(+)(aq)+2e^(-)hArrH_(2)(g)""0.000 Fe^(3+)(aq)+2e^(-)hArrFe^(2+)(aq)""0.770 which is the strongest reducing agent

Answer»

ZN(s)
Cr(s)
`H_(2)(G)`
`Fe^(2+)(aq)`

Solution :More negative is the reduction potential, HIGHER will be the REDUCING property, i.e., the power to give up ELECTRONS.
Discussion
7920.

The spin only magnetic moment value (in Bohr magneton units) of Cr(CO)_(6) is :

Answer»

0
2.84
4.9
5.92

Solution :`[overset(0)Cr(CO)_(6)] IMPLIES d^(6) to t_(2G)^(2, 2, 2)eg^(0, 0)`
Discussion
7921.

Which principle is used in chromatographic separation ?

Answer»

ADSORPTION 
HYDRATION 
PRECIPITATION 
DECOMPOSITION 

ANSWER :A
Discussion
7922.

Which of the following metal chlordie will give chromyl chloride test ?

Answer»

NaCl
KCl
AgCl
`SbCl_(3)`

ANSWER :A::B
Discussion
7923.

Which of the following forms vortex rings?

Answer»

`P_(2)O_(5)`
`PH_(3)`
`NH_(3)`
`P_(4)O_(10)`

SOLUTION :`PH_(3)` FORMS VORTEX RINGS.
Discussion
7924.

Write the formulas of the following co-ordination compounds i) tetramminediaquacobalt (III) chloride ii) tris (ethane-1,2-diamine) chromium (iii) chloride iii) potassium tetracyanonickelate (ii) iii) potassium tetracyanonickelate (ii) (iv) amminebromidochloridonitritoplatinate (II) v) dichloridobis(ethane-1, 2-diamine) platinum (IV) nitrate vi) iron (III) hexacyanoferrate (ii) vii) tris(ethane-1,2-diamine) chromium (III) chloride

Answer»

Solution :i)`[Co(NH_(3))_(4)(H_(2)O)_(2)]Cl_(2)`
ii) `[CR(en)_(3)]Cl_(3)`
iii) `[K_(2)[NI(CN)_(4)]`
iv) `[Pt(NH_(3))BrCl(ONO)]^(-)`
V) `[PtCl_(2)(en)_(2)](NO_(3))_(2)`
vi) `Fe_(4)[Fe(CN)_(6)]_(3)`
vii) `[Cr(en)_(3)]Cl_(3)`
Discussion
7925.

Which one of the not a conductor of electricity ?

Answer»

`NaCl_(("aqueous"))`
`NaCl_(("SOLID"))`
`NaCl_(("molten"))`
`Ag_(("METAL"))`

SOLUTION :In solid state, NaCl does not dissociated into ions so it does not conduct ELECTRICITY.
Discussion
7926.

Which of the following statement is incorrect for a photochemical reaction?

Answer»

Photochemical reactions are complex reactions.
Overall ORDER of photochemical reactions is always zero.
Only the first STEP of such reactions follows zero order kinetics.
The RATE of such reactions depends on the intensity of RADIATIONS absorbed.

Answer :B
Discussion
7927.

Which one of the following gases can deplete ozone layer in the upper atmosphere

Answer»

Ammonia
Methane
Carbon monoxide
Sulphur dioxide

Solution :Methane (hydrocarbons), AEROSOLS, FREON GAS and nitrogen oxide destroy ozone LAYER in upper atmosphere (STRATOSPHERE)
Discussion
7928.

What is the outer shell electronic configuration of the chalcogens?

Answer»

SOLUTION :`ns^(2)np^(4)` where `n(2-6)` is the NUMBER of the OUTERMOST SHELL of the chalcogens.
Discussion
7929.

Which following chalcogon is more occur in earth crust contains same no. of S and P electrons

Answer»

S
TE
O
Se

Answer :C
Discussion
7930.

Which of the followingstatement is false

Answer»

Artificial silk is derived from CELLULOSE
Nylon-66 is an example of elastomer
The repeat unit in natural rubber is ISOPRENE
Both starch and cellulose are POLYMERS of glucose

SOLUTION :Nylon-66 is an example of fibres.
Discussion
7931.

Which of the following sodium halides has the highest melting point ?

Answer»

NaF
NaCl
NaBr
NaI

Answer :A
Discussion
7932.

What is order of radioactive decay ?

Answer»

SOLUTION :FIRST ORDER
Discussion
7933.

The volume of SO_2produced at S.T.P. by the combustion of 50 g of sulphur containing 4% sand by weight will be

Answer»

33.6 L
22.4L
11.2 L
44.8 L

Solution :Amount of SAND `= (50 xx 4)/(100) = 2g`
Amount of sulphur = 50 - 2 = 48 G
`underset(32g)(S) + O_2 to underset(22.4L)(SO_2)`
32g of sulphur at S.T.P. GIVE `SO_2` = 22.4 L
48 g of sulphur at S.T.P.Give `SO_2`
` = (22.4)/(32) xx 48 = 33.6`
Discussion
7934.

What are haloalkanes and haloarenes ?

Answer»

Solution :The replacement of hydrogen atom(s) in an saturated aliphatic HYDROCARBON andaromatic hydrocarbon by HALOGEN atom(s) results in the formation of alkyl halide (haloalkane) and ARYL halide (haloarene), respectively.
Haloalkanes contain halogen atom(s) bonded to the `sp^(3)` hybridised carbon atom of an alkyl GROUP whereas haloarenes CONTAINS halogen atom(s) bonded to `sp^(2)` carbon atoms(s) of an aryl group.
Discussion
7935.

What is Luca. reagent ?

Answer»

Solution : It is a mixture of CON. HC and ANHYDROUS `ZnCl_(2)`
Discussion
7936.

When concentrated hypo solution is added to AgNO_(3) solution a white ppt is formed. With excees of hypo a complex is formed. The oxidation state and coordination number of central metal ion in the anion are:

Answer»

`+3,6`
`+1,2`
`+3,4`
`+1,8`

ANSWER :B
Discussion
7937.

Which dicarboxylic acid is presence of dehydrating agent is least reactive to give an anhydride ?

Answer»




ANSWER :B
Discussion
7938.

Which of the following azeotropes is not correctly matched ?

Answer»

`HNO_3` (68%) +`H_2O`(32%) ,Maximum BOILING AZEOTROPE , boiling point =393.5 K
`H_2O`(43%) + HI(57%) : Minimum boiling azeotrope , boiling point =290 K
`C_2H_5OH` (95.5%) + `H_2O` (4.5%) : Minimum boiling azeotrope , boiling point = 351.15 K
Chloroform (93.2%) +`C_2H_5OH`(6.8%) : Minimum boiling azeotrope, boiling point =332.3 K

SOLUTION :`H_2O` (43%) and HI (57%) MAKE maximum boiling azeotropic MIXTURE on boiling at 400 K.
Discussion
7939.

Which test is used to distinguish between primary, secondary and tertiary alcohol?

Answer»

SOLUTION :LUCAS TEST
Discussion
7940.

The salts of La^(3+) are colourless. Explain.

Answer»

Solution :(i) `LA^(3+)` has electronic configuration, `[Xe]4F^(@)`
(ii) Since there are no UNPAIRED electrons in 4f- ORBITAL, `f rarr f` transition is not possible. HENCE `La^(3+)` ions do not absorb radiations in visible region, and they are colourless.
Discussion
7941.

Which of the following graphs correctly represents the variation of beta= -((dV)/(dP))//V with P for an ideal gas at constant temperature

Answer»




ANSWER :A
Discussion
7942.

What will be the molality of a solution having 18g glucose (m.wt. = 180) dissolved in 500 g of water:

Answer»

1 m
0.5 m
0.2 m
2 m

Answer :C
Discussion
7943.

The uranium (mass no. 238 and at no. 92) emits an alpha-particle, the product has the mass no. and at .no:

Answer»

236 and 92
234 and 90
238 and 90
236 and 90

Answer :B
Discussion
7944.

Define limiting molar conductivity?

Answer»

Solution :The CONDUCTIVITY of an electrolyte at INFINITE dilution called LIMITING MOLAR conductivity.
Discussion
7945.

Which of the following stetments is not correct regarding the geometry of acetylene ?

Answer»

the CARBON atoms in acetylene involve sp-hybridisation
`H-C-C` BOND angle in acetylene is `180^(º)`
in acetylene, there are one `SIGMA` and two `PI` bonds
the `C-C` bond length in acetylene is more than the bond length in ETHYLENE.

Solution :Carbon-carbon bond length in acetylene is less than the bond length in ethylene.
Discussion
7946.

Which of the following match is incorrect?

Answer»


SOLUTION :`K_(3)[Co(o X )_(3)]` is INNER orbital complex with `d^(2)sp^(3)` HYBRIDISATION.
Discussion
7947.

Which one of the following is formed when acetic acid is heated with phosphorous pentoxide?

Answer»

`CH_3COCH_3`
`CH_3CONH_2`
`CH_4`
`(CH_3CO)_2O`

SOLUTION :`(CH_3CO)_2O`
Discussion
7948.

The shape of BrF_(3)

Answer»

Linear
Bent (T ) shaped
Square PYRAMIDAL
Pentaganal BI pyramidal

Solution :`BrF_(3)`
Discussion
7949.

Which is a basic salt

Answer»

PBS
`PbCO_(3)`
`PbSO_(4)`
`2PbCO_(3).Pb(OH)_(2)`

Solution :Because it STILL contain two HYDROXYL group.
Discussion
7950.

Whichof the followingcomplexes haslowest molarconductance

Answer»

`CoCI_(3). 3NH_(3)`
`CoCI_(3).4NH_(3)`
`CoCI_(3).5NH_(3)`
`CoCI_(3).6NH_(3)`

Solution :Molar conductance is the condcting power of all the ions produced by dissolving1 gmole an electrolye thereforemolarconductance `prop`NUMBER of ions produced

form the abvoe table it is clear that molar condcution of the complex WILLBE in the FOLLOWING order `a LT b lt C lt d`
Discussion