21.

Point out the false statement.

• Colloidal sols are homogeneous

• Colloids carry + ve or - ve charges

• Colloids show Tyndall effect

• The size range of colloidal particles is 10-1000 $\stackrel{°}{\mathrm{A}}$

Which of the following statements regarding Lanthanides is false?

• All lanthanides are solid at room temperature

• Their usual oxidation state is +3

• They can be separated from one another by ion-exchange method

• Ionic radii of trivalent lanthanides steadily increases with increase in atomic number

Nitrogen dioxide is not produced on heating

• KNO₃

• Pb(NO₃)₂

• Cu(NO₃)₂

• AgNO₃

In the solid state, PCl₅ exists as

• [PCl₄]^- and [PCl₆]⁺ ions

• covalent PCl₅ molecules only

• [PCl₄]⁺ and [PCl₆]^-

• covalent P₂Cl₁₀ molecules only

The acid in which O-O bonding is present is

• H₂S₂O₃

• H₂S₂O₆

• H₂S₂O₈

• H₂S₄O₆

The metal which can be used to obtain metallic Cu from aqueous CuSO₄ solution is

• Na

• Ag

• Hg

• Fe

If radium and chlorine combine to form radium chloride, the compound would be

• half as radioactive as radium

• twice as radioactive

• as radioactive as radium

• not radioactive

Which of the following arrangements is correct in respect of solubility in water?

• CaSO₄ > BaSO₄ > BeSO₄ > MgSO₄ > SrSO₄

• BeSO₄ > MgSO₄, > CaSO_4, > SrSO_4, > BaSO₄

• BaSO₄> SrSO₄ > CaSO₄ >MgSO₄ > BeSO₄

• BeSO₄ > CaSO₄, > MgSO₄ >SrSO₄ > BaSO₄

If $\mathrm{p}°$and p are the vapour pressure of the pure solvent and solution and n₁ and n₂ are the moles of solute and solvent respectively in the solution then the correct relation between p and p° is

• $\mathrm{p}°=\mathrm{p}\left[\frac{{\mathrm{n}}_1}{{\mathrm{n}}_1+{\mathrm{n}}_2}\right]$

• $\mathrm{p}°=\mathrm{p}\left[\frac{{\mathrm{n}}_2}{{\mathrm{n}}_1+{\mathrm{n}}_2}\right]$

• $\mathrm{p}=\mathrm{p}°\left[\frac{{\mathrm{n}}_2}{{\mathrm{n}}_1+{\mathrm{n}}_2}\right]$

• $\mathrm{p}=\mathrm{p}°\left[\frac{{\mathrm{n}}_1}{{\mathrm{n}}_1+{\mathrm{n}}_2}\right]$

Ionic solids with Schottky defect may contain in their structure

• cation vacancies only

• cation vacancies and interstitial cations

• equal number of cation and anion vacancies

• anion vacancies and interstitial anions