How many unshared pair of electrons are present in water molecule?

Options

A. One
B. Zero
C. Two
D. Three

Explanation

To determine how many unshared pairs of electrons are present in a water molecule (H₂O), follow these steps:

### Step 1: Identify the molecular formula
The molecular formula of water is H₂O, which means it consists of two hydrogen atoms and one oxygen atom.

**Hint:** Remember that the subscript in the formula indicates the number of each type of atom in the molecule.

### Step 2: Determine the valence electrons
Oxygen has 6 valence electrons, while each hydrogen atom has 1 valence electron. Therefore, the total number of valence electrons in the water molecule is:

- Oxygen: 6 electrons
- Hydrogen: 1 electron × 2 = 2 electrons
- Total: 6 + 2 = 8 valence electrons

**Hint:** Valence electrons are the electrons in the outermost shell of an atom that can participate in bonding.

### Step 3: Draw the Lewis structure
In the Lewis structure of water, the oxygen atom is in the center, bonded to two hydrogen atoms. The oxygen atom shares one of its electrons with each hydrogen atom to form covalent bonds. This uses 4 of the 8 valence electrons (2 for each bond).

**Hint:** In a Lewis structure, shared pairs of electrons (bonds) are represented by lines between atoms.

### Step 4: Count the unshared (lone) pairs of electrons
After forming bonds with the two hydrogen atoms, the oxygen atom has 4 valence electrons remaining. These 4 electrons are not involved in bonding and are arranged as 2 lone pairs.

**Hint:** Lone pairs are pairs of valence electrons that are not shared with another atom.

### Step 5: Conclusion
In the water molecule (H₂O), there are 2 unshared pairs of electrons on the oxygen atom.

**Final Answer:** There are 2 unshared pairs of electrons in a water molecule.