Question

question 4. which of the following diagrams has arrows that point in the direction of increasing atomic radius? four diagrams with red arrows and radio buttons omitted here

Explanation:

Step1: Recall atomic radius trends

Atomic radius increases down a group (vertical) and decreases across a period (horizontal, left to right). So down (arrow down) and left (arrow left) should be increasing.

Step2: Analyze each diagram

• First diagram: Down (good) but right (bad, radius decreases right).
• Second diagram: Right (bad) and up (bad, radius decreases up).
• Third diagram: Down (good) and left (good, radius increases left).
• Fourth diagram: Up (bad) and left (good, but up is wrong).

So the third diagram (with down arrow and left arrow) has arrows in increasing atomic radius direction. Wait, no—wait, the third diagram: vertical arrow down (increasing) and horizontal arrow left (increasing, since left to right radius decreases, so left is increasing). Wait, let's recheck. Wait, the options: let's see the third diagram's arrows: vertical down (group: down increases) and horizontal left (period: left increases, since right decreases). So yes, third diagram? Wait no, wait the fourth option? Wait no, let's check the arrows again. Wait the problem is which has arrows in direction of increasing. So down (group) and left (period) are increasing. So the diagram with vertical arrow down and horizontal arrow left. Looking at the options, the third diagram (third from top) has vertical down (red arrow down) and horizontal left (red arrow left). Wait, no, the third diagram's horizontal arrow is left, vertical is down. Yes. Wait but let's check the options:

Wait the four diagrams:

1. Vertical down, horizontal right.

1. Vertical up, horizontal right.

1. Vertical down, horizontal left.

1. Vertical up, horizontal left.

Atomic radius: down a group (increase), left across a period (increase, since right across period, radius decreases). So the arrows should be down (vertical) and left (horizontal). So the third diagram (third option) has vertical down (increasing) and horizontal left (increasing). So that's the one. Wait but let's confirm:

• Down a group: each period down, more electron shells, so radius increases. So vertical arrow down is correct.

• Across a period: left to right, effective nuclear charge increases, radius decreases. So left is increasing, right is decreasing. So horizontal arrow left is correct.

So the diagram with vertical down and horizontal left (third diagram) is correct. Wait but in the options, the third diagram (third from top) has vertical down (red arrow down) and horizontal left (red arrow left). So that's the answer.

Answer:

The third diagram (the one with vertical red arrow pointing down and horizontal red arrow pointing left)