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7151.

Which is larger, an He^(+) ion with an electron in an orbit with n=3 or an Li^(2+) ion with an electron in an orbit with n=5?

Answer»

`He^(+)`
`LI^(2+)`
both equal
none of these

Answer :B
Discussion
7152.

Which one of the following is nearest to the nucleus?

Answer»

6S
4f
5d
6p

Answer :A
Discussion
7153.

The units of cell constant are____.

Answer»

SOLUTION :`CM^(-1)` or `m^(-1)`
Discussion
7154.

What are detergents? How are they classified? Why are detergents preferred over soaps?

Answer»

Solution :Detergents are sulphonate or hydrogen sulphate SALTS of long chain hydrocarbons containing 12-18 CARBON atoms.
Types of detergents
(i) CATIONIC detergents
(ii) Anionic detergents
(iii) Non-ionic detergents
Advantages of detergents over soaps: UNLIKE soaps they work well EVEN with hard water. They can work well even in acidic water. They are more effective than soaps.
Discussion
7155.

Which of the following nitro-compounds behave as an scid in the presence of strong alkaki?

Answer»

Primary
Secondary
Tertiary
Both A and B

Answer :A
Discussion
7156.

Which of the following has open book-structure

Answer»

`SCl_(2)`
`S_(2)Cl_(2)`
`SF_(4)`
`SF_(2)`

Answer :B
Discussion
7157.

Write the products obtained when benzyl phenylether is heated with HI.

Answer»

SOLUTION :PHENOL and BENZYL IODIDE.
Discussion
7158.

Three isomeric hydrocationsC_(9) H_(12) [(A),(B),(C)] oxide to C_(9) H_(6)O_(6) [(D),(E),(F)] while(D) may give three different monoethyl esters, (E) may fromonly two and (F) only one. Idenity compounds (A) to (F).

Answer»

Solution :`D.U` in `C_99) H_(12) = ((2n_(C) + 2)-n_(H))/(2)`
`= ((2xx9+2)-12)/(2) = 4^(@)`
`4 D.U` suggets that it contains benzene ring. On OXIDIATION `(A),(B)`, `(C)` give `C_(9) H_(6)O_(6)`, whicvh suggests three `(COOH)` groups. Therefore `(A), (B), (C)` contain three `(Me)` groups whicvh on oxidation give three `(COOH)` groups. The three isomers of `C_(9) H_(12)` are:
Discussion
7159.

Which compaounds are aromatic? For any compound that is not aromatic, state why this is so.

Answer»


SOLUTION :N/A
Discussion
7160.

Whichofthefollowingis thestrongestbase ?

Answer»

` C_ 6H_ 5 NH _ 2`
` CH_3NH _ 2`
` NH_3`
`CH _ 3CONH _ 2`

Solution :Basicnatureofamine is duetothepresence oflon E pair ofelectronson NITROGENATOM which isacid. Dueto` + I `effectof`-CH _3`GROUP ,`CH _ 3 NH _2`isthe strongestbase.
Discussion
7161.

The velocity of an electron in Bohr's first orbital of la H-atom is 2.16xx10^(6)ms^(-1). Its velocity in the second orbit would be

Answer»

`1.08xx10^(6)MS^(-1)`
`0.54xx10^(6)ms^(-1)`
`4.32xx10^(6)ms^(-1)`
`8.64xx10^(6)ms^(-1)`

Solution :VELOCITY `prop 1/N`
`(v_(2))/(v_(1))=(n_(1))/(n_(2))`
`:.v_(2)=v_(1)xx(n_(1))/(n_(2))=2.16xx10^(2)xx1/2`
`=1.08xx10^(5)ms^(-1)`
Discussion
7162.

What happens when (i) a pressure greater than the osmotic pressure is applied on the solution side separated from solvent by a semipermeable membrane ? (ii) acetone is added to pure ethanol ?

Answer»

Solution :(i) Solvent from the solution will move towards the solvent compartment. This is called reverse osmosis.
(II) In PURE ethanol, molecules are hydrogen bonded. On ADDING acetone, its molecules get in between the host molecules and BREAK some of the hydrogen bonds between them. Due to WEAKENING of interactions, the solution shows positive deviation from Raoult.s law.
Discussion
7163.

Write the chemical equations involved in the preparation of elemental boron from mineral colemanite.

Answer»

SOLUTION :`Ca_(2)B_(6)O_(11)+4SO_(2)+11H_(2)Oto2Ca(HSO_(3))_(2)+6H_(3)BO_(3)`
`2H_(3)BO_(3)overset(Delta)toB_(2)O_(3)+3H_(2)O, B_(2)O_(3)+2AL to Al_(2)O_(3)+2B`
Discussion
7164.

When an electric cell is charged then

Answer»

VOLTAGE of cell increases
electrolyte of cell dilutes.
RESISTANCE of cell increase
None of these.

Solution :When an ELECTRIC cell is charged its voltage increases.
Discussion
7165.

Write the IUPAC name of K_(2)[Zn(OH)_(4)].

Answer»

Solution :`k_(2)[ZU(OH)_(2)]`
IUPAC NAME : POTASSIUM dihydroxozincate (II)
Discussion
7166.

What is the maximum volume of water required to dissolve 1g of CaSO_(4) at 298 K, K_(sp)(CaSO_(4))=9.1xx10^(-6).

Answer»

5.0 L
8.6 L
`3.0xx10^(-3)L`
2.44 L

ANSWER :D
Discussion
7167.

Write one similarity and one difference between the chemistry of lanthanoids and that of actinoids.

Answer»

Solution :Similarity : Both are inner TRANSITION ELEMENTS i.e., electrons are being filled in second LAST shell.
Difference : Actinoid contraction from ELEMENT to element is GREATER than lanthanoid contraction.
Discussion
7168.

XeF_(4)+H_(2)Oto

Answer»

`XeO_(3)`
`XE`
`HF`
`O_(2)`

Answer :A::B::C::D
Discussion
7169.

Which of the following is not correctly matched

Answer»

`{:("COMPOUND" ,,,,"Use"),((1)"Ethanoic acid" ,,,,"Solvent"):}`
`{:("Compound" ,,,,"Use"),((2)"Ester of benzoic acid" ,,,,"Perfumes"):}`
`{:("Compound" ,,,,"Use"),((3)"Sodium benzoate" ,,,,"Preservatives"):}`
`{:("Compound" ,,,,"Use"),((4)"IODOFORM" ,,,,"Aneasthetic"):}`

Answer :D
Discussion
7170.

Whichof the following elements is present as impurity to the maximum extent in the pig iron?

Answer»

Manganese
Carbon
Silicon
Phosphorus

Answer :B
Discussion
7171.

Two Daniel cells contain the same solution of ZnSO_4 but differ in the CuSO_4 solution. The emf of the cell containing 0.5 M CuSO_4 is higher than the other cell by 0.06V. Calculate the concentration of CuSO_4 in the other cell.

Answer»


ANSWER :`[CU^(2+)]=0.5/10^(1//5)`
Discussion
7172.

The unit of ebulioscopic constant is …….

Answer»

K kg `MOL^(-1)` or K `("MOLALITY")^(-1)`
mol kg `K^(-1)` or `K^(-1)` (molality)
kg `mol^(-1)K^(-1)` or `K^(-1)("molality")^(-1)`
K mol `kg^(-1)` or K (molality)

SOLUTION :`Delta T_(B)=K_(b).m`
`K_(b)=(Delta T_(b))/(m)=(K)/("Molality")=(K)/(mol kh^(-1))="K kg mol"^(-1)`.
Discussion
7173.

What happens when a mixture of acetylene and hydrogen is passed over heated Lindlar's catalyst

Answer»

ETHANE and water are formed
Ethylene is formed
ACETYLENE and ethane are formed
NONE of these

Solution :`UNDERSET"Acetylene"(CH-=CH)+H_2undersetunderset(Pb.BaSO_4)"CATALYST"overset"lindlar's"to underset"Ethylene"(CH_2=CH_2)`
Discussion
7174.

Which mechainsm is not seen during the hydrolysis of ester ?

Answer»

`A_(AC^(2))`
`B_(AC^(2))`
`A_(AL^(2))`
`B_(AL^(2))`

Solution :`A_(AL^(2))` is not found during ESTER hydrolysis as `H_(2)O` is a POOR nucleophile.
Discussion
7175.

Which one of the following conclusions could not be derived from Rtherford's alpha- particle scattering experiments?

Answer»

Most of the space in the ATOM is empty.
The radius of the atom is about `10^(10)` m while that of nucleus is `10^(-15)` m
Electrons MOVE in a circular PATH of fixed energy called orbits.
Electrons and the nucleus are held TOGETHER by electrosatic forces of attraction.

Answer :C
Discussion
7176.

Which of the following is not antibiotic ?

Answer»

Tetracylin
Neomycin
Carbomycin
Cyclohexane

Answer :D
Discussion
7177.

The salt on heating does not give brown coloured gas is:

Answer»

`LiNO_3`
`KNO_3`
`PB(NO_3)_2`
`AgNO_3`

ANSWER :B
Discussion
7178.

The vapour pressure of solution of 5 g of acetic acid in 100 g of water at 25^(@)C was 23.40 torr and of the same mass of acetic acid in 100 g of benzene war 70 torr. Assuming acetic acid to be non-volatile, find out its physical state in the two solution, Given P_(H_2)^(@)o=23.756 and P_(C_6H_(6))^(@)=72.5 "torr at"25^(@)C.

Answer»


Solution :We have to calculate the observed molar mass of acetic in both solutions.
(a) in water solution.
`(P_(H_(2)O)^(@)-P_(S))/P_(S)=(eta_(CH_(3)COOH))/(eta_(H_(2)O))`
`P_(H_(2)O)^(@)=23.756" TORR", P_(S)=23" torr", eta_(CH_(3)COOH)=(5g)//m_(CH_(3)COOH),`
`eta_(H_(2)O)=((100g))/((18"g mol"^(-1)))=100/18mol`
`((23.756-23.4)"torr")/(23.4"torr")=((5g))/(M_(B))XX((18"mol"^(-1)))/(100),M_(B)=(23xx(5g)xx(18"mol"^(-1)))/(0.356xx100)=59.16" g mol"^(-1)`.
(b) In banzene solution.
`P_(C_(6)H_(6))^(@)=72.5" torr", P_(S)=70"torr", n_(CH_(3)COOH)=(5g)//m_(CH_(3)COOH),`
`n_(C_(6)H_(6))=((100g))/((78"g mol"^(-1)))=((100)/(78)mol),((72.5-70)"torr")/(70"torr")=((5g))/M_(B)xx(78"mol"^(-1))/100`
`M_(B)=(70.0)/(2.5)xx(5xx78("g mol"^(-1)))/100=109" g mol"^(-1)`
(c) Predicting physical state of acetic ACID in the two solutions.
`"Normal molar mass of "CH_(3)COOH=60" g mol"^(-1)`
`"Observed molar mass in water "=59.16" g mol"^(-1)`
`"Observed molar mass in benzene "= 109.2" g mol"^(-1)`
The value clearly show that acetic acid remains as monomer in water and DIMER in benzene because of intermolecular hydrogen bonding.
Discussion
7179.

Which of the following is not a method of concentration of Ores?

Answer»

Froth floatation 
CALCINATION 
LEACHING 
HYDRAULIC washing 

ANSWER :B
Discussion
7180.

Write structures of the products of the following reactions :

Answer»

SOLUTION :
Discussion
7181.

Write reactions and conditions required for the following conversion: (i) Aniline to benzne (ii) Methylamine to methylcyanide (iii) Propanenitrile to ethylamine (iv) m-Bromoaniline to m-bromophenol (v) Nitrobenzene to 2,4,6- tribromoaniline.

Answer»

SOLUTION :
(II) `underset("Methylamine")(CH_(3)NH_(2))overset(HNO_(2))(to)CH_(3)OH overset(PCl_(5))(to)CH_(3)Cl overset(KCN)(to) underset("Methyl cyanide.)(CH_(3)C-=N`
(iii) `underset("Propanenitrile")(CH_(3)CH_(2)C-=N)+H_(2)O underset(H_(2)O_(2))overset(OH^(-))(to) underset("Propanamide")(CH_(3)CH_(2)-overset(O)overset(||)(C)-NH_(2))underset(KOH) overset(Br_(2))(to) underset("ETHANAMINE")(CH_(3)CH_(2)NH_(2))`
Discussion
7182.

Which of the following compounds is coloured

Answer»

`TiCl_(3)`
`FeCl_(3)`
`CoCl_(2)`
All of these

Solution :The compounds having METAL ions with unpaired electrons, are coloured. THUS, in `TiCl_(3)`
`Ti^(3+) = [Ar]3d^(1) (` one unpaired electron ) in `FeCl_(3)`
`Fe^(3+)= [Ar]3d^(5) (` Fiveunpaired electrons)in `CoCl_(2)`
`Co^(2+) = [Ar]3d^(7)` ( Three unpaired electrons )
Hence, all compoundsare coloured.
Discussion
7183.

What is being used as a laboratory desiccant?

Answer»

SOLUTION :ANHYDROUS `CaCl_(2)`
Discussion
7184.

Which of the following in not part of green chemistry?

Answer»

PHOTO CHEMISTRY
SONO chemistry
NUCLEAR chemistry
Biochemistry

Solution : Nuclear chemistry
Discussion
7185.

What will be the effect of temperature on the constant?

Answer»

SOLUTION :Rate constant of a reaction increases with the increase in temperature . In case of most homogeneousreactions , the value of rate constant increases by 2 to 3 times forevery `10^(@)C` rise in temperature . The exact dependence of the rate constant on temperature is given by Arrhenius equation, `K=Ae^(-E_(a)//RT)` ,where A is the frequency factor and `E_(a)` is activation energy of the reaction.
As T increases,`E_(a)//RT` DECREASES and `E^(-E_(a)//RT)(=(1)/(e^(E_(a)//RT)))`
increases and hence , the value of k increases .
Discussion
7186.

Toluene is obtained by reaction of mixture of chlorobenzene and methyl chloride with Na metal in dry ether. This reaction is called ……

Answer»

Wurtz FITTING reaction
Fitting reaction
Grignard reaction
FRIEDEL crafts reaction

ANSWER :A
Discussion
7187.

Which of the following can be used as monomer in polymerixation reaction

Answer»

`CH_(3)CH_(2)CI`
`CH_(3)CH_(2)OH`
`C_(6)H_(6)`
`C_(6)H_(3)`

ANSWER :D
Discussion
7188.

Total number of lone pair of electrons in XeOF_(4) is

Answer»

0
1
2
3

Answer :B
Discussion
7189.

Tick the wrong statement :

Answer»

Amorphous solids are ISOTROPIC.
Amorphous solids are PSEUDO solids.
Amorphous solids are super cooled liquids.
Amorphous solids have LONG range order.

Answer :D
Discussion
7190.

What is the initial product of the acidic hydrolysis of a cyanide

Answer»

A primary AMIDE
An isocyanide
An isocyanate
A nitrile

Solution :`RCNunderset(H^(+))overset(H_(2)OrarrCH_(3)CONH_(2)UNDERSET(H^(+))overset(H_(2)O)rarrCH_(3)COOH+NH_(3)`
Discussion
7191.

When Zn is added to CuSO_(4) solution , copper is precipitated because of :

Answer»

reduction of Zn
hydrolysis of `CuSO_(4)`
OXIDATION of Zn
reduction of `SO_(4)^(2-)` ions.

Answer :C
Discussion
7192.

Which of the following statements is incorrect for Be?

Answer»

Most of its compounds are largely covalent
`BeCl_(2)` has bridged covalent structure and is a LINEAR molecule above 1200 K
It has distintive group properties due to samller size and high electronegativity
It from `Be^(2+)` ions because of the LOWER VALUE the sum of Ist and 2nd L.E.

Answer :D
Discussion
7193.

What is water gas equilibrium ?

Answer»

Solution :The equilibrium involved in the reaction between carbon dioxide and hydrogen, has MANY industrial applications and is called WATER GAS equilibrium.
`CO_(2)+H_(2)tounderset(("water gas"))(CO+H_(2)O)`
Discussion
7194.

Which is not an example of gaseous air pollutants ?

Answer»

OXIDES of halogens
Oxides of sulphur
Oxides of carbon
Oxides of nitrogen

Answer :A
Discussion
7195.

When an orange coloured crystallccompound [A] was heated withcommon salt and concentrated sulphuricacid , an orange red colouredgas [B] wasevolved. The gas [B] on passingthrough NaOH solution gave a yellow solution [C] . Thesolutionon reactingwith an aqueous solution of lead acetate gave a yellow precipitate. The yellow solution [C] containsmainly

Answer»

Sodium sulphate
Sodium CHROMATE
Sodium dichromate
Potassium chromate.

SOLUTION :(b) The yellow solution (C) contains sodium chromate `(Na_(2)CrO_(4))` which is formed on reacting chromyl chloride with sodium hydroxide (NAOH) solution
`CrO_(2)Cl_(2)+4NaOH to underset("(yellow solution)")(Na_(2)CrO_(4))+2NaCl+2H_(2)O`
Discussion
7196.

When an orange coloured crystallccompound [A] was heated withcommon salt and concentrated sulphuricacid , an orange red colouredgas [B] wasevolved. The gas [B] on passingthrough NaOH solution gave a yellow solution [C] . Thesolutionon reactingwith an aqueous solution of lead acetate gave a yellow precipitate. The crystalline compound [A] is:

Answer»

COBALT nitrate
manganese sulphate
Potassium dichromate.
Ammonium dichromate.

Solution :(c) The available information SUGGESTS that the orange coloured compound is `K_(2)Cr_(2)O_(7)`.
Discussion
7197.

When an orange coloured crystallccompound [A] was heated withcommon salt and concentrated sulphuricacid , an orange red colouredgas [B] wasevolved. The gas [B] on passingthrough NaOH solution gave a yellow solution [C] . Thesolutionon reactingwith an aqueous solution of lead acetate gave a yellow precipitate. This gas [B] is :

Answer»

Chlorine
bromine
CHROMYL choride
nitrogen percipitate.

Solution :(C) The orange red GAS formed during the reaction is of chromyl chloride `(CrO_(2)Cl_(2))`
Discussion
7198.

Which one of the following relationship is correct ?

Answer»

`PH=(1)/([H^+])`
`pH=log_(10)[H^+]`
`log_(10)pH=[H^+]`
`pH=log_(10).(10)/([H^+])`

Answer :D
Discussion
7199.

Whilch of these is not a monomer for a high molecular mass silicone polymer?

Answer»

`Me_(3)SICL`
`PhSiCl_(3)`
`MeSiCl_(3)`
`Me_(2)SiCl_(2)`

ANSWER :A
Discussion
7200.

What happens when? (i) Formic acid is heated with conc. H_(2)SO_(4) (i) Dry chlorine is passed through acetic acid in presenece of sunlight (iii) Oxalic acid is heated with glycerol. (iv) Formic acid is reacted with ammoniacal silver nitrate solution Glacial acetic acid is heated at 973 K (vi) Formic acid is heated with Fehling's solution (vii) Ammonium acetate is dry distilled. (viii) Acidified potassium permanganate is added to oxalic acid (ix) Oxalic acid is heated. (x) Maleic acid is heated. (xi) A carboxylic acid is treated with lithium aluminium hydride. (xii) Acetic acid reacts with thionyl chloride. (xiii) Tartaric acid is treated with hydrogen iodide. (xiv) Lactic acid is heated. (xv) Citric acid is refluxed with hydriodic acid.

Answer»

SOLUTION :
Discussion