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Pickout the incorrect statement
  • a)
  • b)
  • c)
  • d)
Correct answer is option 'C'. Can you explain this answer?

Situ Verma answered
Tautomers represent 2 keto-enol forms in equilibrium. but here enol form leads to aromatic compound which is highly stable ,so here in option c the the keto form once converted to enol form cant be reverted back.So it is a reaction not 2 isomers

Number of molecule that show fluxional behavior among. CH4,CF4,PCI5,PF5,BrF5,SF6,XeO3 is _________
    Correct answer is '3'. Can you explain this answer?

    Saikat Ghoshal answered
    Fluxional behavior among molecules

    Fluxional behavior refers to the rapid interchange of positions of two or more atoms or groups in a molecule. It is a type of isomerism that occurs due to the low energy barrier between two or more isomeric forms of the molecule. The following is the number of molecules that show fluxional behavior among CH4, CF4, PCI5, PF5, BrF5, SF6, XeO3.

    CH4
    CH4 is a tetrahedral molecule with four hydrogen atoms bonded to a central carbon atom. It has no possibility of fluxional behavior because all the hydrogen atoms are identical, and there are no other atoms or groups that can interchange their positions.

    CF4
    CF4 is a tetrahedral molecule with four fluorine atoms bonded to a central carbon atom. It also has no possibility of fluxional behavior because all the fluorine atoms are identical, and there are no other atoms or groups that can interchange their positions.

    PCI5
    PCI5 is a trigonal bipyramidal molecule with five chlorine atoms bonded to a central phosphorus atom. It shows fluxional behavior because the axial and equatorial positions interchange rapidly due to the low energy barrier. This process is known as pseudorotation.

    PF5
    PF5 is also a trigonal bipyramidal molecule with five fluorine atoms bonded to a central phosphorus atom. It shows fluxional behavior for the same reason as PCI5.

    BrF5
    BrF5 is a square pyramidal molecule with five fluorine atoms and one bromine atom bonded to a central bromine atom. It shows fluxional behavior because the axial and equatorial positions interchange rapidly due to the low energy barrier.

    SF6
    SF6 is an octahedral molecule with six fluorine atoms bonded to a central sulfur atom. It does not show fluxional behavior because all the fluorine atoms are identical, and there are no other atoms or groups that can interchange their positions.

    XeO3
    XeO3 is a trigonal planar molecule with three oxygen atoms bonded to a central xenon atom. It shows fluxional behavior because the oxygen atoms interchange their positions rapidly due to the low energy barrier. This process is known as Berry pseudorotation.

    Conclusion
    Out of the given molecules, three molecules show fluxional behavior, namely PCI5, PF5, and XeO3. This behavior is due to the low energy barrier between the isomeric forms of these molecules, which allows them to interchange their positions rapidly.

    The pH of 10-7 HCI solution is 
    • a)
      7
    • b)
      6.8
    • c)
      6.4
    • d)
      7.4
    Correct answer is option 'A'. Can you explain this answer?

    Sinjini Nair answered



    On solving the equation, x = 0.62 x 10-7
    {Negative value of x will be neglected}

    The volume of gases NH3, CO2 and H2 gas adsorbed by 1 gm charcoal at 300 K lie in the order ?
    • a)
      CO2 > NH3 > H2 
    • b)
      NH3 > CO2 > H2 
    • c)
      NH3 > H2 > CO2 
    • d)
      H2 > CO2> NH3
    Correct answer is option 'B'. Can you explain this answer?

    More readily soluble and easily liquifiable gases such as NH3/HC1/C12 and SO2, are adsorbed more than H2/N2.
    i.e.. adsorption
    proportional to intemiolecular interaction,
    proportional to molecular mass,
    proportional to ease of liquidation,
    proportional to 'a’.
    proportional to ciitical temperature (Te.
    Therefore, order of adsoiption of gases:
    SO2 > NH3 > HC1 > CO2, > CH4 > CO > N2 > H2

    Which of  the following test is used for the detection of aldoses?
    • a)
      Seliwanoff's test
    • b)
      Fehling’s test
    • c)
      Bendict’s test
    • d)
      Bromine water test
    Correct answer is option 'A'. Can you explain this answer?

    Seliwanoff's test is a chemical test that distinguishes between aldose and ketose sugars. A mixture of concentrated HCl and resorcinol of 3ml is added to the sugar. Then the solution is boiled for a little time. If it is a ketose sugar like fructose and sucrose is the solution turns cherry red.  

    In [Ni(PNP)X]2 [NiX4] complex, the total coordination number of metal ion is______________
    (X is a uninegative monodentate ligand)
      Correct answer is '12'. Can you explain this answer?

      The compound [Ni(PNP)X]2 [NiX4] where PNP (tridentate) =
      (C6H5)2PCH2CH2NRCH2CH2P(C6H5)2 the total coordination number of metal ion is 12.

      Nickel forms a gaseous compound of the formula Ni(CO)x. The value of x given that under the same conditions of temperature and pressure methane effuses 3.25 times faster than the compound is _____(answer should be an integer). (Given : Ni = 58.7)
        Correct answer is '6'. Can you explain this answer?

        Solution:

        Effusion rate is inversely proportional to the square root of molar mass.

        For methane, effusion rate (r) is given as:

        r = 1/√(16)

        For Ni(CO)x, effusion rate (r') is given as:

        r' = 1/√(58.7 + 12 +16x)

        The ratio of effusion rates is given as:

        r/r' = 3.25

        Substituting the values of r, r' and solving for x, we get:

        x = 6

        Therefore, the value of x for the gaseous compound Ni(CO)x is 6.

        The more stable conformation of the following compound
        • a)
        • b)
        • c)
        • d)
        Correct answer is option 'C'. Can you explain this answer?

        Tejas Goyal answered
        In the given compound, all substituent in cis position (above the plane). So, all group must be in up side.

        π-boncl length between C-C atoms. f.i and v is calculated by using the empirical formula,
        Rμv = 1.52Å - 0.186 Å Pμv
        where Pμv= is π - bond order between μ and v C -atom .
        According to HM O theory. delocalization energy o f Benzene is 2|β|. Then T-bond length in Benzene is
        • a)
          1.53 Å 
        • b)
          1.39 Å
        • c)
          1.33 Å
        • d)
          1.23 Å
        Correct answer is option 'B'. Can you explain this answer?

        Mahi Dasgupta answered
        Since, delocalization energy = 2|β|
        So, one extra delocalizedT-bond Benzene.
        The total energy of π-bond = 4(According to HMO Theory)
        Since, there are 6(C- C ) bond in benzene.
        So. each (C-C) bond has 4/6 π-bond = 2/s = 0.66
        Now. by using formula,
        Rμv = 1.52Å - 0.186 Å x 0.66 = 1.39 Å

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