An element of atomic mass `40` has `2,8,8,2`, as the electronic configuration. One of the following statement regarding this elements is not correct?

Options

A. it forms an basic oxide
B. It belongs to II A group
C. It belongs to IV period
D. It forms an acidic oxide

Explanation

To solve the question regarding the element with atomic mass 40 and electronic configuration 2,8,8,2, we will follow these steps:

### Step 1: Determine the Atomic Number
The electronic configuration given is 2,8,8,2. To find the atomic number, we add the electrons in each shell:
- 1st shell: 2 electrons
- 2nd shell: 8 electrons
- 3rd shell: 8 electrons
- 4th shell: 2 electrons

Total = 2 + 8 + 8 + 2 = 20

### Step 2: Identify the Element
The atomic number 20 corresponds to the element Calcium (Ca) on the periodic table.

### Step 3: Analyze the Statements
Now, we need to evaluate the statements provided regarding this element:

1. **It forms a basic oxide**:
- Calcium is a metal and metals typically form basic oxides. Therefore, this statement is correct.

2. **It belongs to the second A group**:
- Calcium is part of the alkaline earth metals, which are in Group 2A of the periodic table. This statement is also correct.

3. **It belongs to the fourth period**:
- Calcium is indeed located in the fourth period of the periodic table. This statement is correct as well.

4. **It forms an acidic oxide**:
- Calcium, being a metal, does not form acidic oxides; instead, it forms basic oxides. Thus, this statement is incorrect.

### Conclusion
The statement that is not correct regarding the element with atomic mass 40 and electronic configuration 2,8,8,2 is that it forms an acidic oxide.

### Final Answer
The incorrect statement is: "It forms an acidic oxide."

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