Question

26. Select the incorrect order for given property
(A) LiH > NaH > KH > RbH (Thermal stability)
By CaCO3 > CaCO3 > K2CO3 (Covalent character)
(C) BeCO3 > MgCO3 > CaCO3 (Ease of oxide formation on heating at same temperature)
(D) BeF2 > MgF2 > CaF2 > SF 2 (Solubility in water)​

Answer 1

Explanation:

the answer is C.

as per given poverty

Answer 2

The correct question is as follows:

Select the incorrect order for the given property.

A) LiH>NaH>KH>RbH (Thermal stability)

B) CdCO3 >CaCO3>K2CO3 (Covenant character)

C) BeCO3>MgCO3 >CaCO3 (Ease of oxide formation on heating at the same temperature)

D) BeF2>MgF2>CaF2>SrF2 (Solubility in water)

Answer:

The incorrect order is option (D) BeF2 > MgF2 > CaF2 > SF 2 (Solubility in water).

Explanation:

For option (A):

• From top to bottom of lA group, as the atomic number of elements increases, the size of the elements also increases.
• That's why bond dissociation energy between elements and hydrogen will decrease and hence require less energy to decompose and thermal stability will also decreases.
• So, LiH is most thermal stable and RbH is less thermal stable.
• So, option A is correct.

For option (B):

• As the atomic number of elements increases, the size of elements increases and covalent character between the elements and carbonates will decreases.
• So, option (B) is correct.

For option (C):

• From the top to the bottom of llA group, as the atomic number of the elements increases, the size of the elements increases.
• So, less sized element carbonates are easily decomposed into oxides and CO2.
• So, option (C) is correct.

For option (D):

• From the top to the bottom of llA group, as the atomic number of the elements increases, the size of the elements increases and bond strength between elements and fluorides will decreases.
• So, they become easy to break and solubilize.
• Hence, BaF2 is the most soluble and BeF2 is least soluble.
• So, the correct order of solubility is,

BaF2 > SrF2 > CaF2 > MgF2 > BeF2.

• So, option (D) is incorrect.

Hence, option (D) is incorrect.

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