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2751.

The standard reduction potential E^(@)(Bi^(3+)//Bi) and E^(@)(Cu^(2+)//Cu) are 0.226V and 0.344V respectively. A mixture of salts of bismuth and copper at unit concentration each is electrolysed at 25^(@)C. To what value can [Cu^(2+)] be brought down before bismuth starts to deposit in electrolysis.

Answer»


SOLUTION :`E_(Cu^(2+)//Cu) = E_(Cu^(2+)//Cu)^(@) +(0.059)/(2) LG c[Cu^(2+)]`
`[Cu^(2+)] = 10^(-4)m`
Discussion
2752.

Which of the following is a path function?

Answer»

INTERNAL energy
ENTHALPY
WORK
Entropy

Solution :Internal energy, enthalpy and entropy are state function but work and heat are PATH FUNCTIONS.
Discussion
2753.

What are chalcogens ? Why are group 16 elements called chalcogens ?

Answer»

Solution :CHALCOGENS means ore forming. The elements of GROUP 16 are called chalcogens because many metals are found under earth.s CRUST in the form of their OXIDES and SULFIDES and a few as selenides and tellurides.
Discussion
2754.

What does it called if the accumulation of molecular species at the surface rather than in the bulk of solid or liquid ?

Answer»

Adsorbent
Adsorbate
ADSORPTION
Catalysis 

SOLUTION :Adsorption
Discussion
2755.

Setting of cement is an

Answer»

EXOTHERMIC REACTION
Endothermic reaction
Neither exothermic nor endothermic
NONE of these

Answer :A
Discussion
2756.

Which of the following has maximum pK_(a) value?

Answer»




Solution :Tertiary alcohols are the weakest acids and HENCE have HIGHEST `pK_(a)` VALUES, i.e., option (d) is correct.
Discussion
2757.

Which one of the alkali metals, forms only, the normal oxide, M_(2)O on heating in air

Answer»

Rb
K
LI
NA

SOLUTION :`2Li+1//2O_(2) to Li_(2)O`
Discussion
2758.

Which one is an outer orbital complex ?

Answer»

`[NI(NH_(3))_(6)]^(2+)`
`[Mn(CN)_(6)]^(4-)`
`[CO(NH_(3))_(6)]^(3+)`
`[FE(CN)_(5)]^(4-)`

SOLUTION :`[Ni (NH_(3))_(6)]^(2+)`is outer orbital complex.
Discussion
2759.

When gas molecules are held to the surface by the formation of chemical bond the heat energy released is nearly equal to ...............

Answer»

40 kJ/mole
800 kJ/mole
400 kJ/mole
4 kJ/mole

Solution :400 kJ/mole
Discussion
2760.

What happens to the colour of litmus paper when a drop of H_2SO_4 is added to it?

Answer»

It TURNS RED to BLUE
It turns blue to red
It GETS destroyed
It is unaffected

Answer :B
Discussion
2761.

XeF_(4)reacts violentlywith water to give

Answer»

`Xe+O_(2)`
`XeO_(3)+O_(2)+HF`
`Xe+O_(2)+HF+ XeO_(3)`
`XeOF_(4)`

ANSWER :C
Discussion
2762.

Which one of following is a wrong statement?

Answer»

The uncertainty principle is `DeltaExxDeltatgeh//4pi`
Half filled and fully filled orbitals have greater stability DUE to greater exchange energy , greater symmetry and more balanced arrangement.
The energy of 2S orbital is less than the energy of 2P orbital in case of Hydrogen like atoms.
De - Broglie's WAVELENGTH is given by `lamda=h/(mv)` , where m = mass of the PARTICLE , v= group velocity of the particle.

Answer :C
Discussion
2763.

Which of the following represents an alkaline earth metal on the basis of atomic nos.(Z) listed ?

Answer»

10
20
30
40

Answer :B
Discussion
2764.

Who observed helium first on the earth :

Answer»

Lother Mayer
Ramsay
Scheele
Rutherford

Answer :B
Discussion
2765.

What will be the effect of temperature on rate constant ?

Answer»

Solution :The effect of temperature on rate of reaction can be explain on the basis of MAXWELL.s energy distribution curve.

At temperature T, point a in the maxwell distribution curve corresponds to the threshold energy. The molecules having energy EITHER equal to or greater than this energy undergo effective collisions to give products. The area a, b, c and d in the curve represent the fraction of the molecules capable of undergoing effective collisions. If the temperature increases say `T^(@)` to `T + 10^(@)`, the distribution curve is flattened and is numberof molecules associated with the threshold energy is INCREASED. `T + 10^(@)` fraction of the molecules capable of effective collisions is represented by area a, b, E and r which is almost two time than at temperature T. So rate constantof a reaction is nearly doubled with rise in temperature by 10.
Discussion
2766.

Two compounds A and B have some percentage composition. The compouds A and B

Answer»

are identical
are isomers
are neither identical nor isomers
All the three are correct

Solution :Converse of law of definite PROPORTION is not TRUE. For EXAMPLE, butane and isobutane have same percentage composition (CHOICE B), acetylene, `C_(2)H_(2)` and benzene, `C_(6)H_(6)` have same percentage composition. As such choice (D) is correct
Discussion
2767.

Why cannot Vitamin C be stored in our body ?

Answer»

SOLUTION :VITAMIN C is SOLUBLE in WATER and so it cannot be stored in the body.
Discussion
2768.

Which of the suggested tests can be used to differentiate the given compound ?

Answer»

`1^(@)` and `2^(@)` AMINE (carbylamine test)
`CH_(3)CHO` and `CH_(3)CH_(2)CHO` (Tollen's test)
`CH_(3)OH` and `CH_(3)CH_(2)OH` (Lucas test)
`CH_(3)COCH_(3)` and `CH_(3)CH_(2)COCH_(3)` (BRADY's test).

Solution :Carbylamine test is given by `1^(@)` AMINES but not by `2^(@)` amines.
Discussion
2769.

Which of the following will not give positive chromyl chloride test ?

Answer»

Copper chloride, `CuCl_(2)`
Mercuric chloride, `HgCl_(2)`
Zinc chloride, `ZnCl_(2)`
ANILINIUM chloride `C_(6)H_(5)NH_(3)Cl`

Solution :`HgCl_(2)` fails to give positive CHROMYL chloride TEST because of its covalent nature i.e., it does not DISSOCIATE to give `Cl^(-)`
Discussion
2770.

Which of the following reaction is/are incorrect?

Answer»




SOLUTION :
Discussion
2771.

Which reagents cannot be used to differentiate phenol and ethanol :

Answer»

NEUTRAL `FeCl_3`
Na-metal
Oxidising AGENT
`I_2` in PRESENCE of base

Answer :B
Discussion
2772.

The vapour pressure of pure benzene at a certain temperature is 0.850 bar. A non - volatile, non - electrolyte solid weighing 0.5 g when added to 39.0 g of benzene (molar mass 78 g mol^(-1)). Vapour pressure of the solution, then, is 0.845 bar.What is the molar mass of the solid substance ?

Answer»

<P>

Solution :The various quantities known to US are as follows:
`p_(1)^(0)=0.850 " bar," p_(1)=0.845`bar
`M_(1)=78.0 g mol^(-1), w_(2) =0.5 g, w_(1)=39 g`
Substituting these VALUES in equation :
`(p_(1)^(0)-p_(1))/(p_(1)^(0))=(w_(2)xx M_(1))/(M_(2)xx w_(1))`
`(0.850 " bar " - 0.845 " bar")/("0.850 bar")=(0.5 g xx 78 g mol^(-1))/(M_(2)xx 39 g)`
THEREFORE, `M_(2)=170 g mol^(-1)`.
Discussion
2773.

Total number of compound among the following have zero dipole moment is//are C CI_(4) , CHCI_(3) ,CH_(2) CI_(2) ,CH_(3) CI, o- m- and p-dichlorobenzene benzyl chloride benzal chloride and benzotrichloride.

Answer»


SOLUTION :N//A
Discussion
2774.

Which of the following is known as super halogen and why?

Answer»

`Cl_2`
`Br_2`
`F_2`
`I_2`

SOLUTION :`F_2` is SUPER HALOGEN
Discussion
2775.

Which of the following is a first order reaction ?

Answer»

`2H_2O_2 (aq)OVERSET(pt) to 2H_2O + O_2 (G) `
`2HI to H_2+I_2`
`2NO_2 to 2NO + O_2`
`2NO + O_2 to 2NO_2`

Solution :Only (a) is a reaction of 1ST order .
Discussion
2776.

Write structures of the compound whose IUPAC names are as follows : 2-Ethoxy-3-methylpentane

Answer»

SOLUTION :`{:(""CH_3-CH-CH-CH_2CH_3),(""|""|),(CH_3-CH_2-O""CH_3):}`
Discussion
2777.

The red coloured compound formed during the Victor Meyer's test for ethyl alcohol is

Answer»

`{:(C_(2)H_(5)-C=NO^(-)Na^(+)),("|"),(""NO_(2)):}`
`{:(C_(2)H_(5)-CH-NO_(2)^(-)Na^(+)),("|"),(""NO):}`
`{:(C_(2)H_(5)-CH-NO_(2)),("|"),(""NO):}`
`{:((C_(2)H_(5))C-NO),("|"),(""NO_(2)):}`

Answer :B
Discussion
2778.

Which of the following oxyacid is not a true peracid ?

Answer»

Perbenzoic ACID
Pernitric acid
Perchloric acid
All of these.

Solution :PER CHLORIC acid - `HClO_(4)`
Discussion
2779.

Which of the following will give linear plots ?

Answer»

LOG (x/m) VERSUS log C
log x/m versus 1/P
m/x verus 1/P
P/(x/m) versus P

Solution :Follows from Freundilich equation (c ) and (d) FOLLOW from LANGMUIR equaton.
Discussion
2780.

Which one of the following characteristic is associated with adsorption ?

Answer»

`DeltaG, DeltaH and DeltaS` all are NEGATIVE.
`DeltaG and DeltaH` are negative but `DeltaS` is POSITIVE
`DeltaG` and `DeltaS` are negative but `DeltaH` is positive.
`DeltaG` is negative but `DeltaH and DeltaS` are positive. 

Solution :`DeltaG, DeltaH and DeltaS` all are negative.
Adsorption is AUTOMATIC process. It release ENERGY. So decreases Antropy.
`therefore DeltaH, DeltaS, DeltaG` All `- ve`
Discussion
2781.

Which among the following is found to be solvent loving in nature?

Answer»

LYOPHILIC
Lyophobic
Gel
Sol

Answer :A
Discussion
2782.

What are the uses of dinitrogen ?

Answer»

SOLUTION :FOLLOWING are the uses of dinitrogen :
(1) Air contains about `79%` dioxygen and `21%` dinitrogen by volume. Hence `N_(2)` dilutes the ACTION of dioxygen.
(2) It is USED for filling electriclamps.
(3) Dinitrogen provides inert atmosphere in the metallurgicalprocesses.
(4) It is used in the manufacture of `NH_(3), HNO_(3), CaCN_(2)` and many other nitrogen compounds.
(5) Liquefied dinitrogen is used as a refrigerant for the preservation of biological materials, food items also as a cryogenic substanceto obtain very low temperature.
Discussion
2783.

Which of the following reaction can be possible with electrochemical cell by using E_(Cl_(2)|2Cl^(-))^(@)=1.36V and E_(Br_(2)|2Br^(-))^(@)=1.09V

Answer»

`Br_(2)+2Cl^(-) to 2Br^(-)+Cl_(2)`
`2Br^(-)+Cl_(2) to Br_(2)+2Cl^(-)`
`2Cl^(-)+2Br^(-) to Cl_(2)+2Br^(-)`
`2Br^(-) +Br_(2) to 2Cl^(-)+2Br^(-)`

SOLUTION :`E_(Cl_(2)|2Cl^(-))^(THETA)=1.36V,E_(Br_(2)|2Br^(-))^(Theta)=1.09V`

Reduction : `Cl_(2)+2e^(-) to 2Cl^(-),E_(Cl_(2)|2Cl^(-))^(Theta)=1.36V`
Oxidation : `2Br^(-)+Br_(2) to 2e,E_(Br_(2)|2Br^(-))^(Theta)=1.09V`
`E_("Reaction")^(Theta)=E_(Cl_(2)|2Cl^(-))^(Theta)-E_(Br_(2)|2Br^(-))^(Theta)`
`=1.36V-1.09V`
=0.27V
So, the one with higher value of `E^(@)` value gives reduction reaction and so, in only reaction (B), in which `Cl_(2)` ACTING as OXIDIZING agent.
Discussion
2784.

Zn, Cd and Hg are included in transition elements even though they have completely filled d-orbitals. Give reason.

Answer»

SOLUTION :These ELEMENTS SHOW all the chemical similarities with other d-block elements, i.e., they show complex formation and VARIABLE oxidation STATES.
Discussion
2785.

Which of the following solution has highest boiling point ?

Answer»

0.01 m glucose
0.01 m `K_2SO_4`
0.01 m `KNO_3`
0.01 m urea

Answer :B
Discussion
2786.

Which contains the same number of molecules as 16 g oxygen

Answer»

16g`SO_(2)`
`32 g SO_(2)`
`16 g O_(3)`
All the above

Answer :B
Discussion
2787.

Which of the following statement is correct about tropolone ?

Answer»


Tropolone has more stability and aromatic CHARACTER than tropane
Tropolone has higher DIPOLE MOMENT than tropane
Tropolone has LOWER boiling point than tropane

Solution :
Discussion
2788.

Which oxidising agent is used for the oxidation of alcohol ?

Answer»

`H_(2)CrO_(4)`
`KMnO_(4)`
PCC
All of these

Solution :All of these
Discussion
2789.

X overset(AgNO_(3))underset(HNO_(3))rarr "Yellow or white ppt." Which of the following cannot be X ?

Answer»


`(CH_(3))_(2)CHCL`

Solution :`X overset(AgNO_(3))underset(HNO_(3))rarr" YELLOW or while ppt."`
The above reaction is not given by

because in bromobenzene `C-Br`bond is so strong that it cannot BREAK, hence does not form ppt. with `AgNO_(3)`.
Discussion
2790.

What is the role of the following chemicals in food?(a) Sodium benzoate(b) Saccharin.

Answer»

Solution :i. Saccharin - ARTIFICIAL SWEETENING agent
II. Sodium benzoate - food PRESERVATIVE.
Discussion
2791.

Which of the following salt liberates a colourless gas on acidification with dil. H_(2)SO_(4) ?

Answer»

`KNO_(2)`
`Na_(2)CO_(3)`
`NaNO_(2)`
`NaHCO_(3)`

Answer :B::D
Discussion
2792.

What is the principle of using ammonia in refrigeration?

Answer»

Solution :AMMONIA is used in refrigeration due to its high heat of VAPOURISATION.
Discussion
2793.

Which is not a water softener ?

Answer»

Calogen
Permuit
`Na_2CO_3`
`Na_2SO_4`

ANSWER :D
Discussion
2794.

The spin magnetic moment of cabalt in the compound, Hg[Co(SCN)_(4)] is :

Answer»

`root_(3)`
`root_(8)`
`root_(15)`
`root_(24)`

Solution :`OVERSET(+2)Hg[overset(+2)Co(SCN)_(4)]d^(7)` (High SPIN)
`e_(g)^(2, 2)t_(2g)^(1, 1, 1)`
`mu=sqrt(3xx(3+2))B.M.`
Discussion
2795.

Vapour pressure of pure liquid solvent A is 0.8 atm when a non-volatile substance B is added to the solventits vapur pressure drops to 0.6 atm. Calculate how many times the mole fraction of A to that of B.

Answer»


ANSWER :C
Discussion
2796.

Turnbull's blue isformed when Fe^(+2) ions are added to K_(3)[Fe(CN)_(6)]_(2)Turnbull's blue is

Answer»

`Fe_(4)[Fe(CN)_(6)]_(3)`
`Fe_(3)[Fe(CN)_(6)]_(2)`
`Fe_(2)[Fe(CN)_(6)]`
All

Answer :b
Discussion
2797.

Which of the following statement regarding hydrides is not correct ?

Answer»

IONIC hydrides are crystalline , non - volatile and non - conducting in solid state
ELECTRON - deficient hydrides act as Lewis ACIDS or electron acceptors
Elements of group - 13 form electron - deficient hydrides
Elements of group 15-17 form electron - precise hydrides

Answer :D
Discussion
2798.

The standard reduction potential values of three metallic cations, X,Y and Z are 0.52, -3.03 and -1.18V respectively. The order of reducing power of the corresponding metals is

Answer»

`YgtZgtX`
`XgtYgtZ`
`ZgtYgtX`
`ZgtXgtY`

Solution :More negative or lower is the reduction potential, more is the reducing property. Thus the reducing power of the CORRESPONDING metal will follow the REVERSE order, i.e., `Y GT Z gt X`.
Discussion
2799.

Zno is ………………..at room temperature but when it is heated it become ………………. In colour

Answer»

SOLUTION :COLOURLESS, YELLOW
Discussion
2800.

Verdigris is:

Answer»

BASIC copperacetate
Basic LEAD acetate
Basic lead
None

Answer :A
Discussion