When H₂O₂ is added to ice cold solution of acidified potassium dichromate in ether and the contents are shaken and allowed to stand

• a blue colour is obtained in ether because of formation of CrO₅

• a blue colour is obtained in ether because of formation of CrO₃

• a blue colour is obtained in ether because of formation of Cr₂(SO₄)₃

• chromyl chloride is formed

500 mL of a sample of water required 19.6 mg of K₂Cr₂O₇ for the oxidation of dissolved organic matter in it in the presence of H₂SO₄. The COD of water sample is

• 3.2 ppm

• 7.2 ppm

• 6.4 ppm

• 4.6 ppm

33.

The chemical formulae of X, Y and Z are

• X	Y	Z
  CaO	Ca(OH)2	NaOH

• NaOH

  CaO

  CaCO3

• NaOH

  Ca(OH)2

  CaCO3

• Ca(OH)2

  NaOH

  CaCO3

The catenation tendency of C, Si and Ge is in the order Ge < Si < C. The bond energies (in kJ mol^-1) of C-C, Si-Si and Ge-Ge bonds, respectively are

• 348, 167, 180

• 348, 180, 167

• 167, 180, 348

• 180, 167, 348

What is correct about the following structure?

• Total stereoisomers = 4

• Number of chiral carbons = 1

• Number of optical isomers= 2

• Number of meso compounds = 2

Number of oxygen atoms shared per Si${\mathrm{O}}_4^{4-}$ tetrahedron in

I. two dimensional sheet structured silicates

II. cyclic silicates and

III. single strand chain silicates respectively are

• 3, 3, 2

• 3, 2, 2

• 4, 3, 1

• 4, 3, 2

KMnO₄ reacts with ferrous sulphate according to the following equation,

Mn${\mathrm{O}}_4^{-}$ + 5Fe²⁺ + 8H^- $\to$Mn²⁺ + 2Fe³⁺ + 4H₂O

Here, 10 mL of 0.1M KMnO₄ is equivalent to

• 50 mL of 0.1 M FesO₄

• 20 mL of 0.1 M FesO₄

• 40 mL of 0.1 M FesO₄

• 30 mL of 0.1 M FeSO₄

Sodium sulphite is used in preserving squashes and other mildly acidic foods due to

• potassium salt has preservative action

• potassium metabisulphite prevents oxidation

• potassium metabisulphite is not influcenced by acid

• sulphur dioxide and sulphurous acid formed, kill bacteria and germs

Ferrous oxide has a cubic structure. The length of edge of the unit cell is 5 Å and the density of the oxide is 4 .0 g cm^-3 Then the number of Fe²⁺ and O^2- ions present in each unit cell will be

• four Fe²⁺ and two O^2-

• four Fe²⁺ and four O^2-

• two Fe²⁺ and four O^2-

• two Fe²⁺ and two O^2-

Which of the following arrangements correctly represents hexagonal and cubic close packed structure respectively?

• ABAB. .. and ACBACB ......

• ABCABC....... and ABAB

• Both have ABCABC.....arrangement

• Both have ABAB.... arrangement