Question

the atom with the largest atomic radius in period 4 (row 4) is -
fe
k
fe
kr

Explanation:

To determine the atom with the largest atomic radius in Period 4, we use the trend of atomic radius in a period: atomic radius decreases from left to right across a period. This is because as we move from left to right, the number of protons (nuclear charge) increases, pulling the electrons closer to the nucleus, thus decreasing the atomic radius.

• Potassium (K) is in Group 1 (leftmost in Period 4).
• Iron (Fe) is in the middle of Period 4 (Group 8).
• Krypton (Kr) is a noble gas at the far right of Period 4 (Group 18).

Following the left - to - right decrease in atomic radius, K is the leftmost among these, so it has the largest atomic radius in Period 4.

Answer:

B. K