In the long or modern form of the periodic table, the element in the periodic table have been divided into four blocks, `s-p-d`-and `f`-. Each period begins with the filling of new energy shell. Two series of `f`-block elements are placed at the bottom of the periodic table.
The element with `Z=39` belongs to

Options

A. `s`-block
B. `p`-block
C. `d`-block
D. `f`-block

Explanation

To determine which block the element with atomic number \( Z = 39 \) belongs to, we can follow these steps:

### Step 1: Identify the Element
The element with atomic number \( Z = 39 \) is Yttrium (Y).

### Step 2: Determine the Electron Configuration
To find the block of the element, we need to write its electron configuration. The atomic number 39 indicates that Yttrium has 39 electrons. The electron configuration can be built up using the order of filling according to the Aufbau principle.

1. The first 36 electrons fill the electron configuration up to Krypton (Kr), which has the configuration:
\[ \text{[Kr]} = 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 \]

2. The next electrons (37th, 38th, and 39th) will fill the 4d and 5s orbitals:
- The 37th electron goes into the 5s orbital.
- The 38th electron also goes into the 5s orbital.
- The 39th electron goes into the 4d orbital.

Thus, the complete electron configuration for Yttrium is:
\[ \text{[Kr]} 5s^2 4d^1 \]

### Step 3: Identify the Block
In the periodic table:
- The **s-block** elements have their last electron in the s orbital.
- The **p-block** elements have their last electron in the p orbital.
- The **d-block** elements have their last electron in the d orbital.
- The **f-block** elements have their last electron in the f orbital.

Since the last electron of Yttrium (39th electron) is in the 4d orbital, Yttrium belongs to the **d-block** of the periodic table.

### Conclusion
The element with \( Z = 39 \) (Yttrium) belongs to the **d-block** of the periodic table.