Which of the following shows how the atomic radius of the elements changes on crossing from left to right in the row of the Periodic Table from potassium to bromine?
To know how to answer this question and similar questions on the IMAT, you will have to memorize the periodic trends;
The atomic radius as you can see increases from the right upper corner all the way to the bottom left of the table.
A higher effective nuclear charge causes greater attraction to the electrons, pulling the electron cloud closer to the nucleus which results in a smaller atomic radius.
We will cover the rest of the periodic trends in future questions.