Multiple Choice QuestionsProperty of the alkaline earth metals that increases with their atomic number
the solubility of their hydroxides in water
the solubility of their sulphates in water
ionisation energy
ionisation energy
A.
the solubility of their hydroxides in water
Electronegativity, as well as ionisation energy both, usually decrease on moving downward a group with an increase in atomic number. The hydroxides and sulphates of alkaline earth metals are ionic solids and the solubility of ionic solids is governed by two factors viz, lattice energy and hydration energy. For solubility hydration, energy > lattice energy.
Hydration energy varies inversely with size, ie, decreases with increase in size. However, lattice energy in case of sulphates, remains almost same with an increase in the atomic number of alkaline earth metals, due to the large size of sulphates ion. Hence, hydration energy only governs the solubility of alkaline earth metal sulphates decrease as the hydration energy decreases on moving downward the II A group.
Which of the following alkaline earth metal sulphates has hydration enthalpy higher than the lattice enthalpy?
CaSO4
BeSO4
BaSO4
BaSO4
In the case of alkali metals, the covalent character decreases in the order
MCl> MI>MBr>MF
MF> MCl> MBr>MI
MF > MCl> MI>MBr
MF > MCl> MI>MBr
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+
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
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