The s-Block Elements

The alkali metals form salt-like hydrides by the direct synthesis at elevated temperature. The thermal stability of these hydrieds decreases in which of the following orders?

• CsH > RbH > KH > NaH >LiH

• KH > NaH> LiH > CsH >RbH

• NaH > LiH >KH> RbH> CsH

• NaH > LiH >KH> RbH> CsH

The correct order of increasing thermal stability of K₂CO₃, MgCO₃, CaCO₃ and BeCO₃ is:

• BeCO₃ < MgCO₃ < K₂CO₃ <CaCO₃

• BeCO₃ < MgCO₃ < CaCO₃ <K₂CO₃

• MgCO₃ < BeCO₃ < CaCO₃ < K₂CO₃

• MgCO₃ < BeCO₃ < CaCO₃ < K₂CO₃

In which of the following the hydration energy is higher than the lattice energy? 

• BaSO₄

• MgSO₄

• RaSO₄

• RaSO₄

The correct order of the mobility of the alkali metal ions in aqueous solution is:

• Li⁺>Na⁺ > K⁺ > Rb⁺

• Na⁺>K⁺ > Rb⁺  > Li⁺

• K⁺ > Rb⁺ >Na⁺ > Li⁺

• K⁺ > Rb⁺ >Na⁺ > Li⁺

Which of the following oxides is most acidic in nature?

• MgO

• BeO

• CaO

• BaO

Among CaH₂, BeH₂, BaH₂, the order of ionic character is

• BeH₂< CaH₂<BaH₂

• CaH₂<BeH₂<BaH₂

• BaH₂<BeH₂<CaH₂

• BeH₂ < BaH₂ < CaH₂

Which of the following is the correct order of stability for the given superoxides?

• KO₂ < RbO₂ < CsO₂

• CsO₂ < RbO₂<KO₂

• RbO₂

• KO₂ < CsO₂ <RbO₂

When excess of NaOH solution is added to aqueous solution of iodine, the colour of solution becomes

• blue

• yellow

• colourless

• pale green

Which of the following compounds has the lowest melting point?

• CaBr₂

• Cal₂

• CaF₂

• CaCl₂

Which of the following metal carbonates decomposes on heating?

• MgCO₃

• Na₂CO₃

• K₂CO₃

• Rb₂CO₃