Which one of the following has the highest melting point?

1. Na

2. Mg

3. K

4. Al

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

The element among the following that does not show inert pair effect is-

An amphoteric  oxide among the following is-

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

It is because inability of ns² electrons of the valence shell to participate in bonding that

1. Sn²⁺ is reducing while Pb⁴⁺ is oxidising agent

2. Sn²⁺ is oxidising while Pb⁴⁺ is reducing agent

3. Sn²⁺ and Pb²⁺ are both oxidising and reducing agent

4. Sn⁴⁺ is reducing while Pb⁴⁺ is oxidising agent