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 will have largest atomic radii?

Options

A. A
B. H
C. G
D. B

Explanation

To determine which of the elements A, B, C, D, E, F, G, and H has the largest atomic radius, we can follow these steps:

### Step 1: Identify the Elements
From the information provided, we know that:
- A and G combine to form an ionic compound that can be extracted from seawater. This suggests that A is a metal (likely sodium, Na) and G is a non-metal (likely chlorine, Cl), forming NaCl (table salt).
- The oxides of A (Na) and B are basic, indicating that B is also a metal (likely magnesium, Mg).
- The oxides of E and F are acidic, suggesting that E is likely phosphorus (P) and F is sulfur (S).
- The oxide of D is neutral, which suggests that D is silicon (Si).

### Step 2: List the Elements in the Same Period
Given that all elements have the same number of electronic shells, they belong to the same period in the periodic table. The elements can be identified as follows:
- A = Na (Sodium)
- B = Mg (Magnesium)
- C = Al (Aluminum)
- D = Si (Silicon)
- E = P (Phosphorus)
- F = S (Sulfur)
- G = Cl (Chlorine)
- H = Ar (Argon)

### Step 3: Determine Atomic Radii Trends
In the periodic table, atomic radius decreases from left to right across a period due to the increasing nuclear charge, which pulls the electrons closer to the nucleus. Therefore, the atomic radii of the identified elements will follow this trend:
- Na > Mg > Al > Si > P > S > Cl > Ar

### Step 4: Identify the Element with the Largest Atomic Radius
From the trend established, sodium (Na) is the first element in the period and has the largest atomic radius compared to the other elements listed.

### Conclusion
Thus, the element with the largest atomic radius among A, B, C, D, E, F, G, and H is **A (Sodium)**.