An element has atomic number 34. Its valency will be

Options

A. 4
B. 6
C. 2
D. 3

Answer

To determine the valency of an element with atomic number 34, we can follow these steps:

### Step 1: Identify the Element
The atomic number 34 corresponds to the element Selenium (Se).

### Step 2: Determine the Electronic Configuration
The electronic configuration of Selenium can be written as:
- Full configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁴
- Short form: [Ar] 4s² 3d¹⁰ 4p⁴

### Step 3: Identify the Valence Electrons
The valence electrons are the electrons in the outermost shell. For Selenium, the outermost shell is the 4th shell, which contains:
- 4s² (2 electrons)
- 4p⁴ (4 electrons)

Adding these together gives:
- Total valence electrons = 2 (from 4s) + 4 (from 4p) = 6 valence electrons.

### Step 4: Determine the Valency
Valency is determined by the ability of an element to lose, gain, or share electrons to achieve a stable electronic configuration (usually that of a noble gas).

- Since Selenium has 6 valence electrons, it can either gain 2 electrons to complete its octet (achieving 8 electrons in the outer shell) or lose 6 electrons to revert to a stable configuration.
- However, in most cases, the common valency is determined by the number of electrons it needs to gain or lose to achieve a stable configuration.

Thus, the common valency of Selenium is 2 (as it typically gains 2 electrons).

### Conclusion
The valency of the element with atomic number 34 (Selenium) is **2**.

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