Which of the following is correct ?

Options

A. The number of electrons present in the valence shell of S in `SF_6` is 12
B. The rates of reactions involving ionic compounds are very slow.
C. According to VSEPR theory `SnCl_2` is a linear molecule
D. The correct order of ability to form ionic compounds among `Na^+,Mg^(2+) and Al^(3+)` is `Al^(3+) gt Mg^(2+) gt Na^+`

Answer

To determine which statement is correct regarding the properties of sulfur in SF6 and other related concepts, let's analyze each option step by step.

### Step 1: Analyze the first statement about SF6
The first statement claims that the number of valence electrons present in sulfur in SF6 is 12.

- **Sulfur (S)** has 6 valence electrons (as it is in group 16 of the periodic table).
- In SF6, sulfur forms six bonds with six fluorine atoms. Each bond involves the sharing of one electron from sulfur and one from fluorine.
- Therefore, in SF6, sulfur effectively shares 6 additional electrons (one from each fluorine), leading to a total of 12 electrons around sulfur.

**Conclusion**: The first statement is correct.

### Step 2: Analyze the second statement about ionic compounds
The second statement suggests that the rate of reactions involving ionic compounds is very slow.

- Ionic compounds typically dissociate into ions in solution, which can lead to relatively fast reactions, especially in aqueous solutions.
- Therefore, this statement is misleading as many ionic reactions can be quite rapid.

**Conclusion**: The second statement is false.

### Step 3: Analyze the third statement about SnCl2
The third statement claims that according to VSEPR theory, SnCl2 is a linear molecule.

- According to VSEPR theory, SnCl2 has a trigonal planar geometry due to the presence of one lone pair on the tin atom, which causes the two chlorine atoms to be positioned at an angle rather than in a straight line.
- Therefore, this statement is incorrect.

**Conclusion**: The third statement is false.

### Step 4: Analyze the fourth statement about ionic compound formation
The fourth statement discusses the order of ability to form ionic compounds, suggesting that Al3+ has a higher ability than Na+.

- The ability to form ionic compounds generally increases with the electropositivity of the metal.
- Sodium (Na) is a group 1 metal and is more electropositive than aluminum (Al), which is a group 13 metal. Thus, Na+ would have a higher tendency to form ionic compounds compared to Al3+.

**Conclusion**: The fourth statement is false.

### Final Conclusion
Based on the analysis of all statements, the only correct statement is the first one regarding the number of valence electrons in sulfur in SF6.

**Correct Answer**: The first statement is correct.

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