Class 12 > PYQ CHEMISTRY > 2017 > Set 2

2017

History 2 Views

Q21
Give reasons :
(i) Acetylation of aniline reduces its activation effect.
(ii) CH₃NH₂ is more basic than C₆H₅NH₂.
(iii) Although –NH₂ is o/p directing group, yet aniline on nitration gives a significant amount of m-nitroaniline.

Q22
Give reasons:
(i) Thermal stability decreases from H₂O to H₂Te.
(ii) Fluoride ion has higher hydration enthalpy than chloride ion.
(iii) Nitrogen does not form pentahalide.

Q24
Write the product(s) in the following reactions :<p><img alt="" src="" style="height:147px; width:300px" /></p>

(b) Give simple chemical tests to distinguish between the following pairs of compounds :
(i) Ethanol and Phenol
(ii) Propanol and 2-methylpropan-2-ol



Or
(a) Write the formula of reagents used in the following reactions :
(i) Bromination of phenol to 2,4,6-tribromophenol
(ii) Hydroboration of propene and then oxidation to propanol.
(b) Arrange the following compound groups i

Q25
(a) Account for the following:
(i) Transition metals form a large number of complex compounds.
(ii) The lowest oxide of transition metal is basic whereas the highest oxide is amphoteric or acidic.
(iii) E0 value for the Mn³⁺/Mn²⁺ couple is highly positive (+1.57 V) as compare to Cr³⁺/Cr²⁺.
(b) Write one similarity and one difference between the chemistry of lanthanoid and actinoid elements.
OR
(a) (i) How is the variability in oxidation states of transition metals different from that of the p-block elements ?
(ii) Out of Cu⁺ and Cu²⁺, which ion is unstable in aqueous solution and why ?

Q26
(a) An element has atomic mass 93 g/mol and density 11.5 g /cm³. If the edge length of its unit cell is 300 pm, identify the type of unit cell.

(b) Write any two differences between amorphous solids and crystalline solids.
Or
(a) Calculate the number of unit cells in 8.1 g of aluminium if it crystallizes in a f.c.c. structure. (Atomic mass of Al = 27 g/ mol)
(b) Give reasons :
(i) In stoichiometric defects, NaCl exhibits Schottky defect and not Frenkel defect.
(ii) Silicon on doping with Phosphorus forms n-type semiconductor.
(iii) Ferrimagnetic substances show better magnetism than antiferromagne

2
3
4