1 Surface Chemistry and Nuclear Chemistry
Which of the following represents soap ?
1) C17H35COOK 2) C17H35COOH 3) C15H31COOH 4) (C17H35COO)2Ca
SOLUTIONS
Soaps are water soluble sodium or potassium salts of fatty acids. Soaps are made from fats or oils, or their fatty acids by treating them chemically with a strong alkali having molecular formula.
C17H35COOK (potassium stearate).
2 D and F Block Elements
Most probable oxidation state of Pb and Sn will be
1) Pb4+ Sn4+ 2) Pb4+ Sn2+ 3) Pb2+,Sn2+ 4) Pb2+,Sn4+
SOLUTION
3 Stoichiometry
The mass of potassium dichromate crystals required to oxidise 750 cm3 of 0.6 M Mohr's salt solution is: (Given molar mass potassium dichromate = 294, Mohr's salt = 392)
1) 0.45 g 2) 2.2 g 3) 22.05 g 4) 0.49 g
4 P – Block Elements
When nitric acid reacts with nitric oxide, a gas is released, which converts H2S into
When nitric acid (HNO3) reacts with nitric oxide (NO), NO2 gas is released which oxidises H2S into sulphur. The reactions are as follows
5 Mole Concept
A person adds 1.71 gram of sugar (C12H22O11) in order to sweeten his tea. The number of carbon atoms added are (mol. mass of sugar = 342)
1) 7.2 x 1021
2) 3.6 x 1022
3) 6.6 x 1022
4) 0.05
Sugar is nothing but sucrose, which has a formula of C??H??O?? and a molecular weight of 342. number of moles of sucrose in 1.71 grams = 0.005 1 mole of sucrose contains Avogadro number(6 x 10²³) of sucrose molecules. As each molecule of sucrose has 12 carbon atoms, 1 mole of sucrose contains 12( 6 x 10²³) of carbon atoms. Therefore 0.005 moles of sucrose contains 0.005 x 12( 6 x 10²³) = 3.6 x 10²² atoms of carbon are added
6 Chemical Thermodynamics
?E° of combustion of iso-butylene is -X kJ mol -1 . The value of ?H° is
1) = ?E° 2) > ?E° 3) = 0 4) < ?E°
7 Basic Principles of Organic Chemistry
A formula of a compound, which gives simple whole number atomic ratio in one molecule of a compound, is called
1) Diastereoisomerism
2) Geometry isomerism
3) Keto-enol isomerism
4) Enantisomerism
8 Surface Chemistry
Which of the following forms cationic micelles above certain concentrations?
1) Sodium dodecyl sulphate 2) Urea 3) Sodium acetate 4) Cetyl trimethyl ammonium bromide
Sodium dodecyl sulphate and sodium acetate form anionic micelles due to larger size anions. Alkyl trimethyl ammonium ion aggregates to form a cationic micelle.
The reaction is as follows:
R(CH3)3NBr → R(CH3)3N+ + Br−
9 Polymers
Which of the following is fully fluorinated polymer?
1) PVC 2) Thiokol 3) Teflon 4) Neoprene
Teflon is polymer of CF2 = CF2 .
10 P – Block Elements
What is the n factor or valancy factor of ozone during the change 2O3? → 3O2?? 1) 2 2) 4 3) 6 4) 8
2O3 → 3O2 2mole O3 ≡ 3mole O2=3×4eq.O2 ≡12 eq.O2 ∴1 moleO3=6eq.O2
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