The elements which constitute `5f`-block are called `"_______ "` with atomic numbers from `"_____"` to `"______"` .

Explanation

To solve the question regarding the elements that constitute the `5f`-block, we can follow these steps:

### Step 1: Identify the `5f`-block elements
The `5f`-block elements are part of the f-block of the periodic table, which includes the inner transition metals. Specifically, the `5f`-block corresponds to the actinide series.

**Hint:** Recall that the f-block elements are divided into two series: the lanthanides (4f) and actinides (5f).

### Step 2: Name the series
The elements in the `5f`-block are called the "actinides." This term refers to the series of elements that fill the 5f subshell.

**Hint:** Think about the naming convention of the f-block elements. The 4f elements are called lanthanides, so what would the 5f elements be called?

### Step 3: Determine the atomic numbers
The atomic numbers for the `5f`-block elements range from 90 to 103. This means that the actinides start with atomic number 90 (which is thorium) and go up to atomic number 103 (which is lawrencium).

**Hint:** Look at the periodic table to find the starting and ending atomic numbers for the actinide series.

### Final Answer
The elements which constitute the `5f`-block are called **"actinides"** with atomic numbers from **"90"** to **"103."**