1 Hydrocarbons
In benzene, all the six C-C bonds have the same length because of :
1) Isomerism 2) chain isomerism 3) resonance 4) hybridisation.
2 Aldehydes Ketones and Carboxylic Acids
The final product formed when acetaldehyde is reduced with sodium and alcohol is
1) Ethane 2) Ethyl alcohol 3) Ethylene 4) All
CH3CHO + 2[H] → CH3-CH2OH [ in presence of Na/ Alcohol]
3 S – Block Elements
Which one is not a mineral of sodium?
1) Chile saltpeter
2) Cryolite
3) Petalite
4) Rock salt
4 Thermodynamics
The heat exchange at constant volume for the decomposition of Silver (I) Oxide is found to be 3.66 kJ. The heat change at constant pressure will be
1) > 30.66 kJ
2) < 30.66 kJ
3) 30.66 kJ
4) unpredictable
Solution
Heat change at constant volume for the decomposition of silver(I) oxide = 30.66 kJ.
Ag2O(s)?2Ag(s)+12O2(g)
Here, Δng=+ve
Thus, ΔH>ΔE
Since, ΔE=30.66kJ, ΔH>30.66kJ.
5 Hydrocarbons
Among the following the compound that decolourises alkaline kMnO4 is 1. C8H8 2. C2H4 3. CH4 4. CCl4
6 Chemical Kinetics
A catalyst in the finely divided state is more efficient because in this state
1) it can react with one of the reactant more efficiently
2) it has larger activation energy
3) it has large surface area
4) all of the above
7 Alcohols Phenols and Ethers
In Zeisel's method for the determination of methoxy groups, a sample of 2.68 gm of a compound (A) gave 14.08 gm of AgI. If the molecular weight of compound (A) is 134, the number of (−OCH3) group(s) in the compound (A) is:
1) 1 2) 2. 3) 3 4) 4
The number of moles of organic compound $$\displaystyle = \frac {2.68}{134} = 0.2 $$ mol. The number of moles of silver iodide $$\displaystyle = \frac {14.08}{234.77} = 0.06 $$ Thus, 0.2 moles of organic compound gives 0.6 moles of $$AgI$$. 1 mole of organic compound will give 3 moles of $$AgI$$. Hence, the number of methoxy groups present in the organic compound is 3.
8 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
SOLUTION
2O3 → 3O2 2mole O3 ≡ 3mole O2=3×4eq.O2 ≡12 eq.O2 ∴1 moleO3=6eq.O2
9 Stoichiometry
Statement 1: In the titration of Na2CO3 with HclHcl using methyl orange indicator, the volume required at the equivalence point is twice that of the acid required using phenolphthalein indicator Statement 2: Two moles of HCl are required for the complete neutralization of one mole of Na2CO3
1)Statement -1 is true; Statement -2 is true ; Statement -2 is a correct explanation for Statement -1 2)Statement -1 is true; Statement -2 is true; Statement -2 is not a correct explanation for Statement -1 3)Statement -1 is true , Statement -2 is false. 4)Statement -1 is false , Statement -2 is true
In presence of methyl orange as indicator the following reaction goes to completion.
Na2CO3 + HCl→NaHCO3+Nacl
NaHCO3+HCl→Nacl+H2O+CO2
10 Surface Chemistry
The volume of gases H2, CH4, CO2 and NH3 adsorbed by 1g of charcoal at 288K are in the order:
1) H2 >CH4 > CO2 > NH3 2) CH2 > CO2 > NH3 > H2 3) CO2 > NH3 > H2 > CH2 4) NH3 > CO2 > CH4 > H2
NH3 > CO2 > CH4 > H2
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