Which pair of elements belong to the same group?

Elements with atomic number 17 and 53

The correct answer is option 3. Elements with atomic number 17 and 53.

To determine which pair of elements belong to the same group, let's identify the groups of the elements based on their atomic numbers:

1. Elements with atomic number 17 and 38:

Atomic number 17 corresponds to Chlorine (Cl).

Atomic number 38 corresponds to Strontium (Sr).

Chlorine (Cl) is in Group 17 (Halogens).

Strontium (Sr) is in Group 2 (Alkaline Earth Metals).

They do not belong to the same group.

2. Elements with atomic number 20 and 40:

Atomic number 20 corresponds to Calcium (Ca).

Atomic number 40 corresponds to Zirconium (Zr).

Calcium (Ca) is in Group 2 (Alkaline Earth Metals).

Zirconium (Zr) is in Group 4 (Transition Metals).

They do not belong to the same group.

3. Elements with atomic number 17 and 53:

Atomic number 17 corresponds to Chlorine (Cl).

Atomic number 53 corresponds to Iodine (I).

Chlorine (Cl) is in Group 17 (Halogens).

Iodine (I) is also in Group 17 (Halogens).

They belong to the same group (Group 17, Halogens).

4. Elements with atomic number 11 and 53:

Atomic number 11 corresponds to Sodium (Na).

Atomic number 53 corresponds to Iodine (I).

Sodium (Na) is in Group 1 (Alkali Metals).

Iodine (I) is in Group 17 (Halogens).

They do not belong to the same group.

Therefore, the pair of elements that belong to the same group is given by option (3):

Elements with atomic number 17 (Chlorine, Cl) and 53 (Iodine, I) belong to the same group (Group 17, Halogens).