Atoms of eight elements A, B, C, D, E, F, G and H have the same number of electronic shells but are different in their outermost shells. It was found that elements A and G combine to form an ionic compound which can also be extracted from sea water. Oxides of the elements A and B are basic in nature while those of E and F are acidic. The oxide of elements D is almost neutral.
Which one of the following elements is likely to be a noble gas?

Options

A. A
B. H
C. D
D. F

Explanation

To determine which of the elements A, B, C, D, E, F, G, and H is likely to be a noble gas, we can analyze the information provided step by step.

### Step 1: Understanding the Elements
We know that all eight elements have the same number of electronic shells, which indicates they belong to the same period in the periodic table. The outermost electrons differ among the elements.

### Step 2: Identifying Ionic Compound
Elements A and G combine to form an ionic compound that can be extracted from seawater. The most common ionic compound extracted from seawater is sodium chloride (NaCl). This suggests that:
- A is likely sodium (Na).
- G is likely chlorine (Cl).

### Step 3: Analyzing Oxides
We are given information about the nature of the oxides of these elements:
- The oxides of A (Na) and B are basic.
- The oxides of E and F are acidic.
- The oxide of D is neutral.

From this, we can deduce:
- Since A is Na, its oxide is Na₂O, which is basic.
- B must be another metal that forms a basic oxide. A likely candidate is magnesium (Mg), whose oxide is MgO, also basic.

### Step 4: Identifying Acidic Oxides
Next, we look at elements E and F, which have acidic oxides:
- A common non-metal that fits this description is phosphorus (P) for E, with oxides like P₂O₅ (acidic).
- For F, sulfur (S) is a good candidate, with oxides like SO₂ and SO₃, which are also acidic.

### Step 5: Identifying Neutral Oxide
Element D has a neutral oxide. Silicon (Si) is known to form SiO₂, which is considered neutral in nature.

### Step 6: Listing the Elements
Based on the deductions:
- A = Na (Sodium)
- B = Mg (Magnesium)
- C = Al (Aluminum)
- D = Si (Silicon)
- E = P (Phosphorus)
- F = S (Sulfur)
- G = Cl (Chlorine)
- H = ? (Noble gas)

### Step 7: Identifying the Noble Gas
In period 3, the noble gas is argon (Ar). Since H is the only element left unassigned, we can conclude:
- H = Ar (Argon)

### Conclusion
The element likely to be a noble gas is **H (Argon)**.

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