Multiple Choice QuestionsWhich one of the alkali metals, forms only the normal oxide, M2O on heating in air?
Rb
K
Li
Li
In the replacement reaction
The reaction will be most favourable if M happens to be
Na
K
Rb
Rb
Which one of the following is present as an active ingredient in bleaching powder for bleaching action?
Ca(OCl)2
CaO2Cl
CaCl2
CaCl2
What is the value of electron gain enthalpy of Na+ if IE1 of Na = 5.1 eV?
-5.1 eV
-10.2 eV
+2.55 eV
+2.55 eV
Match (I) with list (II) for the compositions of substances and select the correct answer using the code given below the lists.
|
|
List I (substance) |
|
List II Composition |
|
A. |
Plaster of Paris |
1. |
CaSO4.2H2O |
|
B. |
Epsomite |
2. |
CaSO4. ½ H2O |
|
C. |
Kieserite |
3. |
MgSO4. 7H2O |
|
D. |
Gypsum |
4. 5. |
MgSO4.H2O CaSO4 |
|
A |
B |
C |
D |
|
3 |
4 |
1 |
2 |
|
A |
B |
C |
D |
|
2 |
3 |
4 |
1 |
|
A |
B |
C |
D |
|
1 |
2 |
3 |
5 |
|
A |
B |
C |
D |
|
1 |
2 |
3 |
5 |
Property 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
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