Some basic concepts of chemistry

suresh gdvm chemadda.net
BASICCONCEPTSOFCHEMISTRY&STOICHIOMETRY JEE/NEETCHEMISTRY
SINGLE CORRECT CHOICE
LEVEL - I
MOLES
1. The number of moles of CaCl2
needed to react with excess of AgNO3
to produce 4.31 gram of AgCl.
(A) 0.030 (B) 0.015 (C) 0.045 (D) 0.060
2. Calcium carbonate reacts with aqueous HCl to give CaCl2
and CO2
according to the reaction, CaCO3
(s)
+ 2HCl(aq)  CaCl2
(aq) + CO2
(g) + H2
O(l).
The mass of CaCO3
is required to react completely with 25 mL of 0.75 M HCl is
(A) 0.1g (B) 0.5 g (C) 1.5 g (D) 0.94 g
3. Chlorine is prepared in the laboratory by treating manganese dioxide (MnO2
) with aqueous hydrochloric
acid according to the reaction
4HCl (aq) + MnO2
(s)  2H2
O(l) + MnCl2
(aq) + Cl2
(g)
The grams of HCl react with 5.0 g of manganese dioxide will be [at.mass of Mn = 55]
(A) 84 g (B) 0.84 g (C) 8.4g (D) 4.2 g
4. 25.4 g of iodine and 12.2 g of chlorine are made to react completely to yield a mixture of ICl and ICl3
.
Calculate the ratio of moles of ICl and ICl3
.
(A) 1 : 1 (B) 1 : 2 (C) 1 : 3 (D) 2 : 3
5. Calculate the weight of iron which will be converted into its oxide by the action of 18g of steam on it.
(A) 37.3 gm (B) 3.73 gm (C) 56 gm (D) 5.6 gm
6. It takes 0.15 mole of ClO-
to oxidize 12.6 g of chromium oxide of a specific formula to Cr2
O7
2-
. ClO-
became Cl-
. The formula of the oxide is (atomic weight Cr = 52, O = 16)
(A) CrO3
(B) CrO2
(C) CrO4
(D) CrO
7. 8 g of sulphur is burnt to form SO2
which is oxidized by Cl2
water. The solution is treated with BaCl2
solution. The amount of BaSO4
, precipitate is
(A) 1 mole (B) 0.5 mole (C) 0.24 mole (D) 0.25 mole
8. 25.0 ml of HCl solution gave, on reaction with excess AgNO3
solution 2.125 g of AgCl. The normality of
HCl solution is
(A) 0.25 (B) 0.6 (C) 1.0 (D) 0.75
GRAVIMETRIC ANALYSIS
9. If ten volumes of dihydrogen gas reacts with five volumes of dioxygen gas, how many volumes of water
vapour would be:
(A) 10 (B) 20 (C) 48 (D) 12
10. A 10.0 g samples of a mixture of calcium chloride and sodium chloride is treated with Na2
CO3
to
precipitate the calcium as calcium carbonate. This CaCO3
is heated to convert all the calcium to CaO
and the final mass of CaO is 1.62 gms. The % by mass of CaCl2
in the original mixture is
(A) 15.2% (B) 32.1% (C) 21.8% (D) 11.7%

CALCULATION OF n-Factor
11. 1.60g of a metal were dissolved in HNO3
to prepare its nitrate. The nitrate on strong heating gives 2g
oxide. The equivalent weight of metal is
(A) 16 (B) 32 (C) 48 (D) 12
12. Hydroxyl amine reduces iron (III) according to following equation
2 2 4 3 2 2 4 2 4NH OH Fe (SO ) N (g) H O FeSO H SO    
which statement is correct
(A) n-factor for Hydroxyl amines is 1
(B) equivalent weight of Fe2
(SO4
)3
is M/2
(C) 6 meq of Fe2
(SO4
)3
is contained in 3 millimoles of ferric sulphate
(D) all of these.
TYPES OF REDOX REACTIONS
13. How many moles of electrons are needed for the reduction of each mole of Cr in the reaction,
22342425 OOH)SO(CrSOHCrO 
(A) 4 (B) 3 (C) 5 (D) 7
TITRATIONS
14. Equal volumes of 1 M each of KMnO4
and K2
Cr2
O7
are used to oxidize Fe(II) solution in acidic medium.
The amount of Fe oxidized will be
(A) more with KMnO4
(B) more with K2
Cr2
O7
(C) equal with both oxidizing agents (D) cannot be determined
15. The normality of a mixture obtained by mixing 100 ml of 0.2 M H2
SO4
with 100 ml of 0.2 M NaOH will
be
(A) 0.05 N (B) 0.1 N (C) 0.15 N (D) 0.2 N
16. A solution of KMnO4
is reduced to MnO2
. The normality of solution is 1.8. The molarity will be
(A) 0.1 M (B) 0.6 M (C) 1.8 M (D) 0.3 M
17. Amongthefollowingwhichstatement isnot correct
(A) HNO2
can act both as a reducingagent and as an oxidizingagent but HNO3
acts onlyas an
oxidizingagent.
(B) The oxidation number of phosphorus can varyfrom –3 to +5.
(C) The reaction between NaOH and H2
SO4
is a redox reaction.
(D) Oxidationnumbercanhavepositive,negative,zeroorfractional values.

18. In redox reaction, H2
O2
oxidizes K4
[Fe(CN)6
] into K+
, Fe3+
, 2
3CO
and 3NO
ions in acidic
medium, then howmanymoles of H2
O2
will react with1 mole of K4
[Fe(CN)6
]
(A) 5moles (B) 9 moles
(C) 8moles (D) 30.5 moles
19. Assuming full decomposition, the volume of CO2
released at STP on heating 9.85 g of BaCO3
(Atomic mass of Ba = 137)will be
(A) 0.84 L (B) 2.24 L
(C) 4.06 L (D) 1.12 L
20. A 20.00 mLsample of Ba(OH)2
solution is titrated with 0.245 (M) HCl. If 27.15 mLof HCl is
required, what is themolarityoftheBa(OH)2
solution
(A) 0.166 M (B) 0.180 M
(C) 0.333 M (D) 0.666 M
21. Benzenediazoniumchloride, 26 5C H N Cl
+ -
,wasdecomposedinthepresenceofhypophosphorous
acid and thenitrogen evolvedafterdryingwas found tobe36.9 ml at oneatmosphere and 27°C.
Theamountof salt takenmust be nearly
(A) 481 mg (B) 240 mg
(C) 210 mg (D) 140 mg
22. Molarityofa4%NaOHsolutionbyweight havingdensity1.2gm/ml will be
(a) 1.2 M (b) 1.4 M (c) 1.6 M (d) 1.8 M
23. Molarityofa4%NaOHsolution(weight/volume)willbe
(a) 1.2 M (b) 1.0 M (c) 1.6 M (d) 0.5 M
24. Normalityof a0.1 M H3
PO4
solutionwill be
(a) 0.2 (b) 0.4 (c) 0.3 (d) 0.05
25. 100 ml of0.01 M H2
SO4
is titratedagainst 0.2 M Ca(OH)2
, volumeof Ca(OH)2
requiredto reach
end point will be
(a) 5 ml (b) 10 ml (c) 20 ml (d) 15 ml

LEVEL - II
MOLES
26. The molar ratio of Fe++
to Fe+++
in a mixture of FeSO4
and Fe2
(SO4
)3
havingequal number of
sulphateioninbothferrous andferricsulphateis
(A) 1 : 2 (B) 3 : 2 (C) 2 : 3 (D) can’t be
determined
27. Calculate thenumber of oxygen atoms required to combine with 7gof N2
to form N2
O3
when
80% of N2
is converted to N2
O3
.
(A) 2.3  1023
(B) 3.6  1023
(C) 1.8  1021
(D) 5.4  1021
28. A welding fuel gas contains carbon and hydrogen only. Burning a small sample of it in oxygen gives
3.38 g carbon dioxide, 0.690 g of water and no other products. A volume of 10.0 L (measured at
STP) of this welding gas is found to weigh 11.6 g. The empirical formula, molar mass of the gas
and molecular formula will be respectively
(A) CH2
,30, C2
H4
(B) CH,30, C2
H2
(C) CH,26, C2
H2
(D) CH2
,26, C2
H4
29. Which of the following has least mass
(A) 2 g atom of nitrogen (B) 3 × 1023
atoms of C (C) 1 mole of S (D) 7.0 g of Ag
VOLUMETRIC & GRAVIMETRICANALYSIS
30. Hydrochloric acid solutions A and B have concentration of 0.5 N and 0.1 N respectively. The volume
of solutions A and B required to make 2 litres of 0.2 N hydrochloric are
(A) 0.5 l of A + 1.5 l of B (B) 1.5 l of A + 0.5 l of B
(C) 1.0 l of A + 1.0 l of B (D) 0.75 l of A + 1.25 l of B
31. Volume of a gas at STP is 1.12 × 10-7
cc. Calculate the number of molecules in it
(A) 3.01 × 1020
(B) 3.01 × 1012
(C) 3.01 × 1023
(D) 3.01 × 1024
32. The mass of BaCO3
produced when excess CO2
is bubbled through a solution of 0.205 mol Ba(OH)2
is approximately
(A) 81 g (B) 40.5 g (C) 20.25 g (D) 162 g
REDOX REACTIONS
33. Which reactiondoesnotinvolveeitheroxidationnorreduction?
(a) 2
2 3VO V O
 (b) Na Na

(c) 2 2
4 2 7CrO Cr O 
 (d) 2
Zn Zn

34. When KMnO4
acts as an oxidizingagent and ultimatelyforms 2
4MnO 
, 2MnO , Mn2
O3
,Mn2+
then thenumberofelectrons transferred ineachcase respectivelyis:
(a) 4, 3, 1, 5 (b) 1, 5, 3, 7 (c) 1, 3, 4, 5 (d) 3, 5, 7, 1
35. The reaction 2 3Cl Cl ClO 
  is :
(a) Oxidation (b) Reduction
(c) Disproportionation (d) Neitheroxidationnorreduction

36. One mole of N2
H4
loses ten moles ofelectrons to from a new compoundy.Assumingthat all the
nitrogen appears inthe new compound.What is the oxidation stateof nitrogen in y.There is not
changeintheoxidationstateofhydrogen:
(a) –1 (b) –3 (c) +3 (d) +5
37. 1 mol offerric oxalate is oxidized byx mol of 4MnO
andalso 1mol of ferrous oxalate is
oxidizedbyymol of 4MnO
inacidicmedium.Theratio(x/y)is:
(a) 2 : 1 (b) 1: 2 (c) 3 : 1 (d) 1 : 3
38. 3 ×10–3
mole K2
Cr2
O7
reacts completelywith 4.5×10–3
mole Xn+
to give 3XO
and Cr3+
. The
valueofnis:
(a) 3 (b) 1 (c) 0 (d) 4
39. Acertainion Xn+
is oxidized successivelyto 2
4XO 
andthen 4XO
byapowerfuloxidizingagent.
Ifthenumberofmoles oftheoxidizingagent requiredinthesuccessivesteps ofoxidationarein
the ratio 4: 1, n is:
(a) 3 (b) 1 (c) 2 (d) 4
CALCULATIONOFn-FACTOR
40. In thefollowingreaction (unbalanced) equivalent wt. ofAs2
S3
is related tomolecularwt.M by:
3 2
2 3 3 2 4 4As S H NO NO H O AsO SO   
     
(a) M/2 (b) M/4 (c) M/28 (d) M/24
41. In the reaction, 4 2 2 2 4 22CuSO 4KI Cu I 2K SO I    theratio of equivalent weight of CuSO4
toitsmolecularweightis:
(a) 1/8 (b) 1/4 (c) 1/2 (d) 1
TITRATIONS
42. A 100 ml solution of 0.1 N HCl was titrated with 0.2 N NaOH solution. The titration was
discontinued after adding 30 ml of NaOH solution. The remaining titration was completed by adding
0.25 N KOH solution. The volume of KOH required for completing the titration is
(A) 70 ml (B) 32 ml (C) 35 ml (D) 16 ml
43. A solution of 10ml 0.1 M FeSO4
was titrated with KMnO4
solutionin acidicmedium. The
amount ofKMnO4
usedwill be:
(a) 5 ml of 0.1 M (b) 10 ml of 0.1 M
(c) 10 ml of 0.5 M (d) 10 ml of 0.02 M
44. What volume of 0.1 M KMnO4
is needed to oxidize 100 mg of FeC2
O4
in acidic solution?
(a) 4.1 mL (b) 8.2 mL (c) 10.2 mL (d) 4.6 mL
45. 60 ml 0.1 M KMnO4
is treated with excess FeC2
O4
in presence of H2
SO4
. The volume of CO2
gas (measured at NTP) obtained is:
(a) 448ml (b) 672ml (c) 224ml (d) 112 ml
46. 10.78 g of H3
PO4
in 550 mLsolution is 0.40 N. Thus this acid:
(a) has beenneutralized to 2
4HPO 
(b) has beenneutralized to 3
4PO 
(c) has been reduced to 2
3HPO 
(d) has beenneutralized to 3 4H PO

VOLUME STRENGTH OF H2
O2
47. The labelling on a bottle of H2
O2
solution is 20 “vol”, then the concentration of H2
O2
in percentage
strength will be:
(A) 3.03 % (B) 5% (C) 4.55% (D) 6.06 %
48. What volume of H2
O2
solution of 22.4 “vol” strength is required to liberate 2240 mL of O2
at NTP ?
(A) 300 mL (B) 200 mL (C) 100 mL (D) 500 mL
LEVEL-III
49. What volume of 1 M FeC2
O4
(ferrous oxalate) solution is required for the complete oxidation of 100
ml of 1 M Fe(SCN)2
solution into Fe3+
, SO4
2-
, CO3
2-
and nitrate ?
(A) 0.7 litre (B) 1 litre (C) 0.8 litre (D) 1.1 litre
50. A solution contains Cu2+
and C2
O4
2-
ions which on titration with 1 M KMnO4
consumes 10 ml of the
oxidizing agent for complete oxidation in acidic medium. The resulting solution is neutralized with
Na2
CO3
, acidified with dil. CH3
COOH and is treated with excess of KI. The liberated iodine requires
25 ml of 1 M of hypo solution, then that will be the molar ratio of Cu2+
to C2
O4
2-
ions in solution ?
(A) 5 : 2 (B) 1 : 2 (C) 2 : 1 (D) 1 : 1
51. In redox reaction, Ba(MnO4
)2
oxidises K4
[Fe(CN)6
) into K+
, Fe3+
, CO3
2-
and NO3
-
ions in acidic
medium, where Ba(MnO4
)2
itself reduces into Mn2+
, than how many moles of Ba(MnO4
)2
will react
with 1 mole of K4
[Fe(CN)6
]
(A) 5 moles (B) 9 moles (C) 8 moles (D) 6.1 moles
52. For 109% labeled oleum if the number of moles of H2
SO4
and free SO3
be x and y respectively, then
what will be the value of ?
x y
x y


(A) 1 (B) 18 (C) 1/3 (D) 9.9
53. A sample of tap water contains 366 ppm of HCO3
-
ions with Ca2+
ion. Now it is removed by Clark’s
method by addition of Ca(OH)2
. Then what minimum mass of Ca(OH)2
will be required to remove
HCO3
-
ions completely from 500 g of same tap water sample
(A) 1 g (B) 0.4 g (C) 0.222 g (D) 0.111 g
54. 55 g Ba(MnO4
)2
sample containing inert impurity is completely reacting with 100 mL of 56 ‘vol’
strength of H2
O2
, then what will be the percentage purity of Ba(MnO4
)2
in the sample ? (Ba – 137,
Mn – 55)
(A) 40% (B) 25% (C) 10% (D) 68.18%
55. An aqueous solution of 0.57 g of KIO3
(formula weight = 214) reacts with excess of KI in presence of
HCl, where both converts into I2
. The liberated I2
consumes certain volume of (0.1 M) Na2
S2
O3
, in
basic medium where it converts into SO4
2-
, then find out the volume of Na2
S2
O3
(in mL) needed to
reach the equivalence point.
(A) 19.97 (B) 29.97 (C) 24 (D) 35
56. The simplest formula of a compound containing 50% of element X (atomic mass 10) and 50% of
element Y (atomic mass 20) is
(A) XY (B) X2
Y (C) XY3
(D)X2
Y3
57. The number of water molecules present in a drop of water (volume 0.0018 ml) at room temperature
is
(A) 6.023 × 1019
(B) 1.084 × 1018
(C) 4.84 × 1017
(D) 5.023 × 1023
58. What will be the volume of CO2
at NTP obtained on heating 10 grams of (90% pure) limestone
(A) 22.4 litre (B) 2.016 litre (C) 2.24 litre (D) 20.16 litre

Some basic concepts of chemistry

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