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2001.

ZnO shows yellow colour on heating due to

Answer»

d-d transition
C-T spectra
Higher polarisation CAUSED by `Zn^(2+)` ion
F-centres

Solution :Among d-block ELEMENTS
Max M.P. of the first transition series=Cr
Min M.P. of SECOND transition series=Cd
Discussion
2002.

Write IUPAC name of

Answer»

SOLUTION :IUPAC NAME : 1, 2, 4, 6 tetrachlorobenzene.
Discussion
2003.

What are the products of auto-photolysis of water?

Answer»

`H_(2)` and`O_(2)`
Steam
`H_(3)O^(+)` and `OH^(-)`
Hydrogen PEROXIDE

Solution :`H_(2)O to H^(+) + OH^(-)`
`UNDERLINE(H_(2)O + H^(+) to H_(3)O^(+))`
`2H_(2)O to H_(3)O^(+) + OH^(-)`
Discussion
2004.

Which hybrid orbitals will form the compound, CH_4

Answer»

`SP^2` and `sp^3`
only`sp^3`
`sp` and `sp^3`
`sp` and `sp^2`

ANSWER :A
Discussion
2005.

Write the mechanism of the following reaction: CH_(3)CH_(2)OHoverset(HBr)(to)CH_(2)CH_(2)Br+H_(2)O

Answer»

SOLUTION :The reaction of ethyl alcohol with HBr to yield bromide proceeds via `S_(N)^(2)` mechanism. The mechanism proceeds through the formation of the transition state. The nucleophile `(BR^(-))` attacks the carbon ATOM from the side near to the -OH group, thus leading to inversion of CONFIGURATION in the final product.
Discussion
2006.

Which hydrolysis in water :

Answer»

AgF
AgCl
AgBr
AgI

Answer :A
Discussion
2007.

What is the two dimensional coordination number of a molecule in square close-packed layer ?

Answer»

Solution :In a square close-packed layer, each ATOM is SURROUNDED by four atoms of NEIGHBOURING squares. Therefore, coordination NUMBER is 4.
Discussion
2008.

The values of dissociation constants of [Cu(NH_(3))_(4)]^(2+) and [Co(NH_(3))_(6)]^(3+) are 1.0xx10^(-12) and 6.2xx10^(-36) respectively. Which complex would be more stable and why ?

Answer»

SOLUTION :Smaller the value of the dissociation constant, more stable is the COMPLEX in the solution. Hence, `[Co(NH_(3))_(6)]^(3+)` is more stable than `[Cu(NH_(3))_(4)]^(2+)` ion.
Discussion
2009.

Which will not be hydrolysed

Answer»

POTASSIUM nitrate
Potassium cyanide
Potassium succinate
Potassium CARBONATE

Solution :Because it is a salt of strong acid and strong BASE.
Discussion
2010.

Which of the following ion is expected to be colourless

Answer»

`Cu^(2+)`
`TI^(4+)`
`V^(3+)`
`Fe^(2+)`

Solution :`Ti^(4+)`
Discussion
2011.

What should be the minimum conditions to show geometrical isomerism ?

Answer»

Restricted rotation about double bond or RING.
Groups which are responsible to SHOW GEOMETRICAL ISOMERISM differ in their relative distance.
Free rotation about SINGLE bond.
Two different groups at both restricted atoms.

Answer :A::B::D
Discussion
2012.

Which of the following can be used in preparation of permanent magnets?

Answer»

Fe
Co 
GD 
All of these 

ANSWER :D
Discussion
2013.

Which of the following statements are correct for Van't Hoff's factor 'I' for a solution of weak electrolyte A_(x) By .

Answer»

`i=1-alpha+Xalpha+Yalpha`
`I gt` 1 at normal DILUTION
"I" increases more rapidly with dilution and attains a limiting value of (x+y) at infinite dilution
the increases in "I" with dilution is DUE to INCREASE in molatriry of solution with dilution .

Answer :A::B::C
Discussion
2014.

When liquid 'A' is treated with a freshly prepared ammoniacal silver nitrate solution, it gives bright silver mirror. The liquid forms a white crystalline solid on treatment with sodium hydrogensulphite. Liquid 'B' also forms a white crystalline solid with sodium hydrogensulphite but it does not give test with ammoniacal silver nitrate. Which of the two liquids is aldehyde ? Write the chemical equations of these reactions also.

Answer»

SOLUTION :The liquid A is an aldehyde. ALDEHYDES give a bright silver mirror when treated with ammoniacal silver nitrate solution. They also form a WHITE crystalline solid on treatment with sodium hydrogensulphite. The REACTIONS are given as under :
Discussion
2015.

The relative lowering of vapour pressure of 0.2 molal solution in which the solvent is Benzene is

Answer»

`15.6xx10^(-4)`
`15.6xx10^(-3)`
`15.6xx10^(-1)`
`0.05`

ANSWER :B
Discussion
2016.

White phosphorus when reacts with nitric acid gives

Answer»

`H_(4)P_(2)O_(6)`
`H_(3)PO_(2)`
`H_(3)PO_(4)`
`H_(3)PO_(3)`

Answer :C
Discussion
2017.

The solublity product of iron (III) hydroxide is 1.6 xx 10^(-39). If X is the solublity of iron (III) hydroxide, then which one of the following expressions can be used to calculate X

Answer»

`K_(sp) = X^(4)`
`K_(sp) = 9 X^(4)`
`K_(sp) = 27 X^(3)`
`K_(sp) = 27 X^(4)`

Solution :The solubility product `(K_(sp))` of a SPARINGLY SOLUBLE SALT at a given temperature may be defined as the product of the molar concentrations of its each raised to the power equal to its number of ions present in the equation representing the dissociation of one molecule of the salt.
`{:(Fe(OH)_(3), hArr ,Fe^(3+)+,3OH^(-)),(,,X,3X):}`
`K_(sp) = [Fe^(3+)][OH^(-)]^(3)`
`:. K_(sp) = X(3X)^(3) = 27 X^(4)`.
Discussion
2018.

Which of the following statements indicates that law of multiple proportion is being followed.

Answer»

Sample of carbon dioxide taken from any source will always have carbon and oxygen in the ratio `1:2`
Carbon forms two oxides namely `CO_(2)` and CO, where masses of oxygen which combine with FIXED MASS of carbon are in the simple ratio `2:1`
When magnesium burns in oxygen, the amount of magnesium taken for the REACTION is equal to the amount of magnesium in magneisum OXIDE formed.
At constant temperature and pressure, 200 mL of hydrogen will combine with 100 mL oxygen to produce 200 mL of water vapour.

Solution :Statement (b) is correct according to the law of multiple proportions.
Discussion
2019.

The same electric current is passed through solutions of ferrous sulphates , FeSO_(4) and silver nitrate, AgNO_(3) . If the amount of iron deposited is (Ag=108, Fe=56, N=14, S=32, O=16)

Answer»

14 g
2.7 g
0.7 g
1.35 g

Solution :`(W_(FE))/(W_(AG))=(E_(Fe))/(E_(Ag))`
`THEREFORE W_(Fe)=(28xx2.7)/(108)=0.7 g`
Discussion
2020.

Which is not correctly matched ?

Answer»

`{:("Complex COMPOUNDS","IUPAC name"),(K[CrF_(4)O],"Potassium tetrafluorooxo chromate(V)"):}`
`{:("Complex compounds","IUPAC name"),(Na[BH(OCH_(3))_(3)],"Sodium hydrido trimethoxy borate (III)"):}`
`{:("Complex compounds","IUPAC name"),([Be(CH_(3)-CO-CH-CO-C_(6)H_(5))_(2)]^(0),"Bis (benzoylacetonato BERYLLIUM (III)"):}`
`{:("Complex compounds","IUPAC name"),(H[AuCl_(4)],"Hydrogen tetrachloro aurate (III)"):}`

Solution :Sodium hydido trimethoxo borate (III)
c) Bis(Benzoyl acetonato) beryllium (O)
Discussion
2021.

When an ecidified solution of ferrous sulphiate is treated with potassium paramagnet solution, the ion which is oxidised is

Answer»

`MnO_(4)^(-)`
`NH_(4)^(+)`
`FE ^(3+)`
`SO_(4)^(2-)`

SOLUTION :`Fe ^(2+)overset("oxidises")TOFE^(3+)`
Discussion
2022.

What are X and Y respectively in the following reaction? X overset(PBr_3)(rarr)C_2H_5Br overset(AgOH(Aq))(rarr)Y

Answer»

`CH_(3)OH , C_(2)H_(6)`<BR>`C_(2)H_(5)OH , C_(2)H_(5)Br`
`CH_(3)COOH , CH_(3)CH_(2)OH`
`C_(2)H_(5)OH, C_(2)H_(5)OH`

Answer :D
Discussion
2023.

Which of the following amino acid is neutral?

Answer»

ASPARTIC acid
Glycine
Lysine
Arginine

Solution :`UNDERSET"Aspartic acid (ACIDIC )"undersetunderset("" CH_2COOH)(|)(H_2N-CH-COOH)`
`undersetunderset"(neutral)""Glycine"(H_2N-CH_2-COOH)`
Discussion
2024.

When the same amount of zinc is treated separately with excess of H_(2)SO_(4) and excess of NaOH, the ratio of volumes of H_(2) evolved is

Answer»

`1:2`
`1:1`
`9:4`
`2:1`

ANSWER :B
Discussion
2025.

To a solution of a substance, gradual addition of ammonium hydroxide results in a brown ppt. which does not dissolve in excess of NH_4 OH. However, when HCl is added to the original solution, a white ppt. is formed. The solution contained

Answer»

LEAD salt
silver salt
mercurous salt
copper salt

SOLUTION :black or brown Hg when treated with HCl gives BACK `Hg_(2)Cl_(2)`
Discussion
2026.

Write the structures of the product of the following reaction CH_3-CH=CH_2 overset(H_2 O //H^+)to

Answer»

SOLUTION :`CH_3-UNDERSET(OH)underset(|)CH-CH_3 ` propan-2-ol
Discussion
2027.

The resistance of a solution A is 50 ohms and that of solution B is 100 ohms both solutions being taken in the same conductivity cell. If equal volumes of solution A and B are mixed, what will be the resistance of the mixture using the same cell ? (Assume that there is no increase in the degree of dissociation of A and B on mixing.)

Answer»

Solution :Let `K_(1)` and `K_(2)` be the specific conductance of the solutions A and B respectively and the constant of the cell be x.
`therefore` for solution A : sp. conductance = conductance `xx` cell constant
`K_(1) = (1)/(50) xx x` ….(1)
For SOLUTON B : sp. conductance `K_(2) = (1)/(100) xx x` .......(2)
When equal VOLUMES of A and B are mixed, both the solutions get doubly diluted , hence their individual contribution TOWARDS the sp. conductance of the mixture will be `(K_(1))/(2)` and `(K_(2))/(2)` respectively and the sp. conductance of the mixture will be `(1)/(2)(K_(1) + K_(2))`.
`therefore` for the mixture: `(1)/(2)(K_(1) + K_(2)) = (1)/(R) xx x`. ......(3)
R is the resistance of mixture)
From eqns. (1), (2) and (3), we get R = 66.67 ohms.
Discussion
2028.

Which of the followingpolymers of glucose is stored by animals?S

Answer»

CELLULOSE
Amylose
Amylopectin
GLYCOGEN

ANSWER :D
Discussion
2029.

Ullmann reaction involves the use of following reactants :

Answer»

Iodobenzene and sodium
Benzene and COPPER
Iodobenzene and copper powder
Benzene diazonium chloride and CU/HCl

Solution :`C_(6)H_(5)I+Cu+C_(6)H_(5)I overset("Dry ether")underset(-Cu l_(2))rarr C_(6)H_(5)-C_(6)H_(5)`
Discussion
2030.

What is meant by unidentate, didentate and ambidentate ligands? Give twoexamples for each.

Answer»

Solution :It is an ION or GROUP which can ATTACK from both sides, e.g., `C -= N^(-)`
Discussion
2031.

Which oxidizing reagent used to oxidise trialkyl borane in presence of aq. sodium hydroxide ?

Answer»

`LiAH_(4)`
`(BH_(3)_(2)`
`H_(2)O_(2)`
All of these

Solution :`H_(2)O_(2)`
Discussion
2032.

Which of the following will not be soluble in sodium hydrogen carbonate?

Answer»

Benzenesulphonic ACID
BENZOIC acid
o-Nitrophenol
2, 4, 6- trinitrophenol

Answer :C
Discussion
2033.

To prepare tert-butyl ethyl ether by Williamson synthesis, the reactants needed are

Answer»

SODIUM ETHOXIDE and sodium TERT butoxide
Sodium ethoxide and tert-butyl bromide
Sodium tert-butoxide and ethyl bromide
Ethyl ALCOHOL and tert-butyl alcohol

Answer :C
Discussion
2034.

What are thermosetting polymers ?

Answer»

Solution :These are semi fluid SUBSTANCES with low molecular masses which when heated in a mould , undergo a permanent change in chemical composition to give a HARD , infusible and insoluble mass. This hardening on heating is due to extensive cross linking between POLYMER chains to give a three -dimensional network solid. Thus , a thermosetting polymer can be heated only once when it undergoes a permanent change and SETS into a solid which cannot be remelted and reworked. For example , bakelite , melamine-formaldehyde polymer , ETC.
Discussion
2035.

Write the dispersed phase and dispersion medium of milk.

Answer»

SOLUTION :LIQUID FATS DISPERSED in liquid in liquid WATER
Discussion
2036.

Which of the following reactions will not occur?

Answer»

`2CU+4I^(-)RARR 2CuI+I_(2)`
`2Fe+6I^(-)rarr 2Fe^(2+)+4I^(-)+I_(2)`
`2Cu^(++)+4Cl^(-)rarr 2CuCl+Cl_(2)`
NONE of the three.

Answer :C
Discussion
2037.

Which of the following statement is correct ? P) pyruvic acid gives haloform test Q) pyruvic acid gives tollen's test R) pyruvic acid undergoes decarboxylation with warm. dil H_2 SO_4 and gives CH_3 CHO S) pyruvic acid undergoes decarbonylation with warm, conc.H_2 SO_4, and gives CH_3 COOH

Answer»

P,Q,R,S
P,Q,R only
R,Q only
Only P

Solution :`CH_3 - overset(O)overset(||)C-COOH` (PYRUVIC ACID)
P) Due to the presence of `CH_3-overset(O)overset(||)` group it GIVES haloform TEST
Q) It undergoes decarboxylation and gives `CH_3 CHO`. Hence it gives tollen.s test
Discussion
2038.

Which of the following alcohol will respond Lucas test slowest ?

Answer»

Secondary BUTYL ALCOHOL
`3^(@)` - butanol
Neo PENTYL alcohol
None of the above

Solution :Neo pentyl alcohol
Discussion
2039.

Which of the following does not show optical activity?

Answer»


ANSWER :A
Discussion
2040.

Which of the following is the wrong statement ?

Answer»

OZONE is DIAMAGNETIC gas
ONCl and `ONO^(-)` are isoelectronic
`O_(3)` molecule is bent
Ozone is violet-black in solid state

Solution :ONCl (8 + 7 + 17 = 32) and `ONO^(-)` (8 + 7 + 8 + 1 = 24) are not isoelectronic.
Discussion
2041.

which of the following does not react with benzene in presence of anhydrous AlCl_3:

Answer»

`C_6H_5Cl`
`C_6H_5CH_2Cl`
`CH_3Cl`
`C_6H_5CH_2CH_2CH_2Cl`

ANSWER :A
Discussion
2042.

Which polymer is used to prepare fishing nets?

Answer»

Nylon-6,6
Nylon-6
Terylenel
BUTYL RUBBER

SOLUTION :Nylon-6,6
Discussion
2043.

Which of the following base is not present in RNA ?

Answer»

ADENIN
URACIL
thymine
CYTOSINE

ANSWER :C
Discussion
2044.

Total number of molecules which can form H-bond among themselves. SiH_(3)OH, HCN, B(OMe)_(3), NHMe_(2), CH_(2)CONH_(2), HCHO, HCOOH, NH_(2)OH, H_(4)SiO_(4)

Answer»


Solution :`B(Ome)_(2) and HCHO` can not FORM H-bond.
Discussion
2045.

Zn, Cd, Hg are sometimes not considered as transition elements. Comment.

Answer»


ANSWER :A
Discussion
2046.

What do you by 20% awueous solution of sodium carbonate ?

Answer»

Solution :This MEANS that 20g of SODIUM carbonate are dissolved in 100 ML od aqueoous solution.
Discussion
2047.

Which one among the following is the correct order of strength of acids?

Answer»

`+1,+5,-2`
`+1,+7,-2`
`0,0,0`
`+1,+7,0`

Solution :OXIDATION is any chemicalreaction that INVOLVES the moving of electrons SPECIFICALLY it MEANS the SIDE that gives away electrons
Discussion
2048.

What are the types of changes in the cathode and anode in electrolytic and electrochemical cells.

Answer»

SOLUTION :
Discussion
2049.

Which of the following gives PH_3 on treatment withwater ?

Answer»

`Ca_3P_2`
`Na_3P`
AIP
All of the above

Solution :All phosphides on TREATMENT with water forms `PH_(3)`.
`Ca_3P_(2)+6HOH to 2PH_(3)+3Ca(OH)_(2)`
`Na_(3)P+3HOH to PH_(3)+3NaOH`
`AIP+3HOH to PH_(3)+AL(OH)_(3)`
Discussion
2050.

Which of the following reaction from benzene carbaldehyde as a product :

Answer»

a,B,C,d
a,b,d,E,
a,b,e,f
a,b,c,d,e,f

Answer :D
Discussion