Which loses weight on exposure to the atmosphere ?

1. Concentrated H₂SO₄

2. Solid NaOH

3. A saturated solution of CO₂

4. Anhydrous sodium carbonate

Which of the following compound is weakest Lewis acid ?

(1) BF₃

(2) BCl₃

(3) BBr₃

(4) BI₃

Which does not show inert pair effect

(1) Al

(2) Sn

(3) Pb

(4) Thallium

Pick the correct statement :

(1) Borax is white crystalline solid containing [B₄O₅(OH)₄]^2- units

(2) Aqueous solution of borax is acidic in nature.

(3) Cobalt gives green colour in borax bead test.

(4) All are incorrect.

Mark the oxide which is amphoteric in character

(1) CO₂

(2) CO

(3) SnO₂

(4) CaO

In B₂H₆ 

(1) there is direct boron-boron bond

(2) the structure is similar to that of C₂H₆

(3) the boron atoms are linked through hydrogen bridges

(4) all the atoms are in one plane

From the B₂H₆ all the following can be prepared except:

(1) H₃BO₃

(2) [BH₂(NH₃)₂]+ [BH₄]-

(3) B₂(CH₃)₆

(4) NaBH₄

Which of the following shows correct Lewis acidic strength order of trihalides of boron ?

(1) BCl₃ > BBr₃ > BF₃ > BI₃

(2) BF₃ < BBr₃ < BCl₃ < BI₃

(3) BF₃ < BCl₃ < BBr₃ < BI₃

(4) BF₃ >BCl₃ > BBr₃ > BI₃

The correct order of ease of hydrolysis is 

1. CCl₄ < SiCl₄ < PCl₅ < AlCl₃

2. AlCl₃ < CCl₄ < PCl₅ < SiCl₄

3. CCl₄ < AlCl₃ < PCl₅ < SiCl₄

4. CCl₄ < AlCl₃ < SiCl₄ < PCl₅

Which compound is formed when iron reacts with carbon?

1. ${\mathrm{FeC}}_2$        2. ${\mathrm{Fe}}_3{\mathrm{C}}_{}$      3. ${\mathrm{FeC}}_3$    4. ${\mathrm{Fe}}_2\mathrm{C}$