42 gm of Mg (At. mass 24) will produce MgO equal to:

Options

A. 1.75mole
B. 17.5 mole
C. 12mole
D. all of the above

Explanation

To solve the question, we need to determine how much magnesium oxide (MgO) can be produced from 42 grams of magnesium (Mg). We will follow these steps:

### Step 1: Write the chemical reaction
The reaction between magnesium and oxygen to form magnesium oxide can be represented as:
\[ 2 \text{Mg} + \text{O}_2 \rightarrow 2 \text{MgO} \]

### Step 2: Calculate the number of moles of magnesium
To find the number of moles of magnesium, we use the formula:
\[ \text{Number of moles} = \frac{\text{Given mass}}{\text{Molar mass}} \]
Given:
- Mass of magnesium = 42 g
- Molar mass of magnesium = 24 g/mol

Calculating the number of moles:
\[ \text{Number of moles of Mg} = \frac{42 \text{ g}}{24 \text{ g/mol}} = 1.75 \text{ moles} \]

### Step 3: Determine the moles of magnesium oxide produced
From the balanced chemical equation, we see that 1 mole of magnesium produces 1 mole of magnesium oxide (MgO). Therefore, the number of moles of MgO produced will be the same as the number of moles of Mg used:
\[ \text{Moles of MgO} = \text{Moles of Mg} = 1.75 \text{ moles} \]

### Step 4: Conclusion
Thus, 42 grams of magnesium will produce 1.75 moles of magnesium oxide (MgO).

### Final Answer:
**1.75 moles of MgO**

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