31.

If the solubility of an aqueous solution of Mg(OH)₂ , be X mole litre then k_sp of Mg(OH)₂ is:

• 4X³

• 108X⁵

• 27X⁴

• 9X

Which of the following molecules forms no inter molecular hydrogen bonds?

• ${\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{OH}$

• HF

• ${\mathrm{CH}}_3{\mathrm{COCH}}_3$

• ${\mathrm{CH}}_3\mathrm{COOH}$

Which of the following metals, Fe, Zn, Pb, Ag and Pt do not give a metal nitrate on treatment with concentrated HNO?

• Fe and Zn.

• Fe and Pt.

• Pb, Ag and pt.

• Fe, Ag and Zn.

The oxidation number of sulphur atoms in peroxomonosulphuric acid H₂SO₅ and peroxodisulphuric acid H₂S₂O₈, respectively are:

• +8 and +7

• +6 and +6

• +4 and +6

• +3 and +3

The rate constant for a first order reaction is 60 s^-1 .The time required to reduce the concentration of the reactant to $\frac{1}{10}\mathrm{th}$ of its initial value is:

• $3.8\times {10}^{-2 \sec }$

• $1097\times {10}^{3 }\sec$

• $1.26\times {10}^{13 }\sec$

• $2.01\times {10}^{13}\sec$

Which of the following statement regarding defect is correct.

• Due to Schottky defect, the density of crystalline solid decreases.

• Due to Frenkel defect, the density of crystalline solid decreases.

• Due to Schottky defect, entropy of solid decreases.

• Due to Frenkel defect, entropy of solid decreases.

Migration of colloidal particles towards the oppositely charged electrode is called:

• Electrosmosis

• Electrophoresis

• Coagulation

• Electrodispersion

When aqueous ammonia is added to green solution of nickel chloride, the colour changes to:

• yellow

• purple

• violet

• violet

Organophosphorus compounds are the most toxic insecticides. The common organophosphorus insecticides is:

• Methoxy chlor

• Dieldrin

• Parathion

• Malathion

In trimeta-phosphate ion, the number of 0 atom P-O-P bonds and unit negative charges are respectively:

• 6,6,3

• 3,6,3

• 9,3,3

• 9,6,3