(Each and every questions are not answered, they will be added soon and in any chaos please comment)

2     A simple ion X+ contains eight protons.

     What is the electronic configuration of X+?

     A     1s2       2s1       2p6

     B     1s2      2s2      2p3

     C     1s2      2s2      2p5

     D     1s2       2s2       2p7


solution:
the proton number is 8 which implies its atomic no, is 8.
hence, the  electronic configuration of the element with atomic number 8 is 1s2, 2s2 2p4.
the ion of the element (atomic no. 8) has one positive charge i.e. it lost one electron.
so, one electron needs to be removed from its electronic configuration.
so the new electronic configuration is 1s2, 2s2 2p3.
(Note: the electron is always removed from the outermost orbital)
the answer is B







solution:
At 1,
the carbon atom is has four bond pair and no lone pair i.e. it has perfect tetrahedral shape and hence bond angel of 109.5 degree.

At 2,
though the carbon atom has four bond pairs, only three bond pairs are counted (the C=O bond has one sigma bond and one pie bond, we neglect the pie bond). And, three bond pairs has a triangular planar shape with bond angle 120 degree.

At 3,
there are two bond pairs and two lone pairs (of oxygen atom). So, two bond pairs and two lone pairs forms a distorted tetrahedral shape and presence of one lone pair distorts the shape by roughly 2.5 degree. So, the bond angle here is 104.5

lets sort this out and in ascending order we get the sequence 3<1<2

so the answer is C







Solution:
The initial step to solve the question of enthalpy is draw the hess cycle. (Note: while drawing the Hess cycle you must apply the oxygen atom to all three reaction on your own)

The Hess cycle is like this:

                                4C + 5H2 + 1.5O2----------------→ C4H10 + 1.5O2  
                                                                                       
                                                              ↘                     ↙
                                                                   CO2 + H2O 


Enthalpy change={(4*-394) + (s*-286)} – (-2877)
                              =-129
(Note: the enthalpy change of combustion is the energy change when ONE MOLE of the element or compound is burnt. Hence, the no. of moles of the compound should be multiplied by its standard enthalpy value.)

The answer is B





9     In a calorimetric experiment 1.60 g of a fuel is burnt. 45 % of the energy released is absorbed by
     200 g of water whose temperature rises from 18 °C to 66 °C. The specific heat capacity of water is
     4.2 J g–1 K–1
      What is the total energy released per gram of fuel burnt?
     A    25 200 J           B    56 000 J           C    89 600 J           D    143 360J

Solution:
Q=msdt
    =200*4.2*(66-18)
    =40320

This is the energy gained by water, which is only 45 percent of the total energy. Lets apply some mathematics now. Assume that the total energy release is x. the equation will be

45 % of x=40320
i.e. x=89600

But, the value is total energy released by the 1.60gm of the fuel and the question asks us to calculate the energy released per gram of fuel.  So, time for some extra mathematics.

1.60gm releases 89600 J
So, I gm releases 89600/1.60 J i.e. 56000J

The answer is B.





Solution:
The equation shows that I mole of ethanol and one mole of ethanoic acid produces one mole of water and ethyl ethanoate. Hence, during equilibrium, (1- x) mol of the ethanol and (1-x) ethanoic acid produces x mol of water and x mole of ethyl ethanoate. Now,

Kc=[x].[x]/[1-x].[1-x]
Or, 2=x/(1-x)

0r, x=2/3

(Note that the value of x is the concentration not volume but we had assumed while performing the calculations that the volume is 1dm3. Hence, the no. of moles is also 2/3)

The answer is B.






solution:
draw the displayed formula of compound for simplification. and the repeat unit is as follow:

     H   H
      |     |
   ─C─C─                           
      |     |
     H  CO2H
       
  in the monomer there is double bond between the carbon carbon atoms of the repeat unit.
hence the answer is C





solution:
the given compound is the ester (─O─C=O) and carboxylic acid produces ester when they are reacted with alcohols. so, it is deduced that the compound X is alcohol.
the formation of ester is in such a way that the part after ─O, not inclusive of C=O is derived from alcohol and rest part after ─O inclusive of C=O is part of carboxylic acid.
in the above compound the part of alcohol is
            O   H  H
             ||    |    |
  H3C─C─C─C─
                   |    |

                  H   H

And in this part the OH group get attached to the Carbon atom and hence it ,molecular formula becomes C4H8O2.
the answer is D







Solution:
note that the no. of carbon atoms has increased in product so it must have reacted with HCN (HCN as the reactant is ketone).
similarly, the reactant is a carboxylic acid and carboxylic acid is produced by the acidic hydrolysis of nitriles. hence the reagent is H2SO4.

so, the answer is B.







only one and two degree alcohols can react with K2Cr2O7/H+. And. among the two, 1 degree alcohols can produce two products i,e. aldehydes and carboxylic acid (when further oxidised). Only, 2 degree alcohols can produce only one product which is ketone no matter hoe long you oxidise it.
so, we are looking for the 2 degree alcohol which is butran-2-ol.
the answer is B.