An f-shell containing 6 unpaired electrons can exchange

• 6 electrons

• 9 electrons

• 12 electrons

• 15 electrons

Which sequence of reactions shows correct chemical relation between sodium and its compounds?

• $\mathrm{Na}+{\mathrm{H}}_2\mathrm{O} \to \mathrm{NaOH}\stackrel{\mathrm{HCl}}{\to }\mathrm{NaCl}\stackrel{{\mathrm{CO}}_2}{\to }{\mathrm{Na}}_2{\mathrm{CO}}_2\stackrel{∆}{\to }\mathrm{Na}$

• $\mathrm{Na}+{\mathrm{H}}_2\mathrm{O} \to \mathrm{NaOH} \stackrel{{\mathrm{CO}}_2}{\to }{\mathrm{Na}}_2{\mathrm{CO}}_3\stackrel{\mathrm{HCl}}{\to }\underset{\left(\mathrm{molten}\right)}{\mathrm{NaCl}} \stackrel{\mathrm{Electrolysis}}{\to }\mathrm{Na}$

Which of the following compounds cannot be prepared singly by the Wurtz reaction?

• C₂H₆

• (CH₃)₂CHCH₃

• CH₃CH₂CH₂CH₃

• All of the above can be prepared

Which of the following oxides is strongly basic?

• TI₂O

• B₂O₃

• Al₂O₃

• Ga₂O₃

Among the following the strongest nucleophile is

• C₂H₅SH

• CH₃COO^-

• CH₃NH₂

• NCC${\mathrm{H}}_2^{-}$

The sodium extract of an organic compound on acidification with acetic acid and addition of lead acetate solution gives a black precipitate. The organic compound contains

• nitrogen

• halogen

• sulphur

• phosphorus

The equivalent conductivity of a solution containing 2.54 g of CuSO₄, per L is 91.0 W^-1 cm²eq^-1. Its conductivity would be

• $2.9 \times {10}^{-3}{\mathrm{\Omega }}^{-1}{\mathrm{cm}}^{-1}$

• $1.8 \times {10}^{-2} {\mathrm{\Omega }}^{-1} {\mathrm{cm}}^{-1}$

• $2.4 \times {10}^{-4} {\mathrm{\Omega }}^{-1}{\mathrm{cm}}^{-1}$

• $3.6 \times {10}^{-3}{\mathrm{\Omega }}^{-1}{\mathrm{cm}}^{-1}$

The half-life of two samples are 0.1 and 0.8 s. Their respective concentration are 400 and 50 respectively. The order of the reaction is

• 0

• 2

• 1

• 4

19.

Purest form of iron is

• pig iron

• wrought iron

• cast iron

• steel

Which has the smallest size?

• Na⁺

• Mg²⁺

• Al³⁺

• P⁵⁺