Science (English Medium) इयत्ता १२ - CBSE Question Bank Solutions for Chemistry

Atomic number of \[\ce{Mn, Fe, Co}\] and Ni are 25, 26, 27 and 28 respectively. Which of the following outer orbital octahedral complexes have same number of unpaired electrons?

(i) \[\ce{[MnCl6]^{3-}}\]

(ii) \[\ce{[FeF6]^{3-}}\]

(iii) \[\ce{[CoF6]^{3-}}\]

(iv) \[\ce{[Ni(NH3)6]^{2+}}\]

An aqueous pink solution of cobalt (II) chloride changes to deep blue on addition of excess of HCl. This is because:

(i) \[\ce{[Co(H2O)6]^{2+}}\] is transformed into \[\ce{[CoCl6]}^{4-}\]

(ii) \[\ce{[Co(H2O)6]^{2+}}\] is transformed into \[\ce{[CoCl4]}^{2-}\]

(iii) tetrahedral complexes have smaller crystal field splitting than octahedral complexes.

(iv) tetrahedral complexes have larger crystal field splitting than octahedral complex.

On the basis of crystal field theory explain why Co(III) forms paramagnetic octahedral complex with weak field ligands whereas it forms diamagnetic octahedral complex with strong field ligands.

Why are low spin tetrahedral complexes not formed?

Give the electronic configuration of the following complexes on the basis of Crystal Field Splitting theory.

\[\ce{[CoF6]^{3-}, [Fe(CN)6]^{4-} and [Cu(NH3)6]^{2+}}\].

Arrange following complex ions in increasing order of crystal field splitting energy (∆_O):

\[\ce{[Cr(Cl)6]^{3-}, [Cr(CN)6]^{3-}, [Cr(NH3)6]^{3+}}\].

\[\ce{CuSO4 . 5H2O}\] is blue in colour while \[\ce{CuSO4}\] is colourless. Why?

Match the complex ions given in Column I with the hybridisation and number of unpaired electrons given in Column II and assign the correct code:

Using crystal field theory, draw energy level diagram, write electronic configuration of the central metal atom/ion and determine the magnetic moment value in the following:

\[\ce{[CoF6]^{3-}, [Co(H2O)6]^{2+}, [Co(Cn)6]^{3-}}\]

Using crystal field theory, draw energy level diagram, write electronic configuration of the central metal atom/ion and determine the magnetic moment value in the following:

\[\ce{[FeF6]^{3-}, [Fe(H2O)6]^{2+}, [Fe(CN)6]^{4-}}\]

Why are different colours observed in octahedral and tetrahedral complexes for the same metal and same ligands?

Toluene reacts with a halogen in the presence of iron (III) chloride giving ortho and para halo compounds. The reaction is ______.

Assertion: In monohaloarenes, further electrophilic substitution occurs at ortho and para positions.

Reason: Halogen atom is a ring deactivator.

Phenol is less acidic than ______.

Phenol can be distinguished from ethanol by the reactions with:

(i) \[\ce{Br2/water}\]

(ii) \[\ce{Na}\]

(iii) Neutral \[\ce{FeCl3}\]

(iv) All the above

Write the IUPAC name of the following compound.

\[\begin{array}{cc}
\phantom{.}\ce{CH3 - CH - CH - CH - CH - CH3}\phantom{}\\
\phantom{......}|\phantom{......}|\phantom{......}|\phantom{.....}|\phantom{........}\\
\phantom{...}\ce{CH3}\phantom{...}\ce{OH}\phantom{...}\ce{C2H5}\phantom{.}\ce{OH}\phantom{...}\end{array}\]

What is denatured alcohol?

Out of 2-chloroethanol and ethanol which is more acidic and why?

Suggest a reagent for conversion of ethanol to ethanal.

Suggest a reagent for conversion of ethanol to ethanoic acid.