Identify the incorrect statement(s):

Options

A. Density of Mg is less than Ca
B. The atomic radius of Mg is greater than that of Ca
C. Mg alloys are used in the contruction of air crafts
D. Mg is used as a reducing agent

Explanation

To identify the incorrect statements regarding magnesium and calcium, we will analyze each statement one by one.

**Step 1: Analyze the first statement**
- The first statement claims that the density of magnesium is less than that of calcium.
- Fact: Magnesium has a higher density than calcium. Therefore, this statement is incorrect.

**Step 2: Analyze the second statement**
- The second statement claims that the atomic radius of magnesium is greater than that of calcium.
- Fact: As we move down the group in the periodic table, the atomic radius increases due to the addition of electron shells. Hence, magnesium, being above calcium in Group 2, has a smaller atomic radius than calcium. Therefore, this statement is also incorrect.

**Step 3: Analyze the third statement**
- The third statement claims that magnesium alloys are used in the construction of aircraft.
- Fact: This statement is true. Magnesium alloys, which often contain elements like aluminum and zinc, are indeed used in aircraft construction due to their lightweight and strength.

**Step 4: Analyze the fourth statement**
- The fourth statement claims that magnesium is used as a reducing agent.
- Fact: This statement is true. Magnesium can act as a reducing agent because it readily oxidizes (loses electrons) to form magnesium oxide, thereby reducing other species in the process.

**Conclusion: Identify the incorrect statements**
- The incorrect statements are:
1. The density of magnesium is less than calcium (incorrect).
2. The atomic radius of magnesium is greater than that of calcium (incorrect).

Thus, the answer is that statements 1 and 2 are incorrect.

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