arrange the following by increasing atomic size. br, ca, kr

Explanation:

Step1: Recall atomic - size trend

Atomic size decreases across a period from left to right due to increasing effective nuclear charge.

Step2: Locate elements in the periodic table

Br (bromine), Ca (calcium), and Kr (krypton) are in the same period (Period 4). Ca is in Group 2, Br is in Group 17, and Kr is in Group 18.

Step3: Arrange by atomic size

Since atomic size decreases across the period, the order of increasing atomic size is Kr < Br < Ca.

Answer:

Kr, Br, Ca