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Among the statements (a)-(d) , the corre...

Among the statements (a)-(d) , the correct ones are :
(a) Lithium has the highest hydration enthalpy among the alkali metals.
(b) Lithium chloride is insoluble in pyridine.
(c) Lithium cannot form ethynide upon its reaction with ethyne.
(d) Both lithium and magnesium react slowly with `H_(2)O`

A

(1),(2) and (4) only

B

(1) and (4) only

C

(2) and (3) only

D

(1),(3) and (4)

Text Solution

AI Generated Solution

The correct Answer is:
To solve the question regarding the correctness of the statements about lithium and its compounds, we will analyze each statement step by step. ### Step-by-Step Solution: 1. **Statement (a): Lithium has the highest hydration enthalpy among the alkali metals.** - **Explanation:** Hydration enthalpy refers to the energy released when an ion is dissolved in water. It is influenced by the charge density of the ion, which is the ratio of the charge to the size (radius) of the ion. Lithium is the smallest alkali metal ion, which gives it the highest charge density. Therefore, lithium indeed has the highest hydration enthalpy among alkali metals. - **Conclusion:** This statement is **correct**. 2. **Statement (b): Lithium chloride is insoluble in pyridine.** - **Explanation:** Lithium chloride has significant covalent character due to the small size of the lithium ion. This property allows it to dissolve in organic solvents, including pyridine. Therefore, lithium chloride is soluble in pyridine. - **Conclusion:** This statement is **incorrect**. 3. **Statement (c): Lithium cannot form ethynide upon its reaction with ethyne.** - **Explanation:** Lithium has a small size and high polarizing power, which results in high ionization energy. This makes it difficult for lithium to lose its outermost electron and react with ethyne to form ethynide. Thus, lithium does not form ethynide. - **Conclusion:** This statement is **correct**. 4. **Statement (d): Both lithium and magnesium react slowly with water.** - **Explanation:** Lithium reacts slowly with water, forming lithium hydroxide and hydrogen gas. Magnesium also reacts slowly with water, especially with hot water or steam, forming magnesium hydroxide and hydrogen gas. Therefore, both metals exhibit slow reactivity with water. - **Conclusion:** This statement is **correct**. ### Final Conclusion: The correct statements are (a), (c), and (d). Therefore, the answer is that statements 1, 3, and 4 are correct.
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