What would cause entropy to increase in a reaction?

A. The products forming a more rigid structure
B. The products forming an ordered pattern
C. The products becoming more spread out
D. The products forming fewer molecules

I think the answer is c or d

Increasing entropy is increasing disorder.

look here
http://chemistry.about.com/od/workedchemistryproblems/a/Entropy-Change-Example-Problem.htm

note - more spread out --> more entropy

(for example solids to gasses :)

And I still think it is Physics :)

Nope. This is AP chemistry.

c is the answer.

For my money I wish physics had kept it.

It’s literally regular chemistry

To determine the correct answer, let's first understand what entropy is. Entropy is a measure of the disorder or randomness in a system. When a reaction occurs, the entropy of the system can either increase or decrease, depending on the changes happening to the system.

For option A, if the products form a more rigid structure, it suggests a decrease in disorder or randomness, which means the entropy of the system would decrease. So, option A is incorrect.

For option B, if the products form an ordered pattern, it also indicates a decrease in disorder. An ordered pattern is less random, so the entropy of the system would decrease. Hence, option B is also incorrect.

Now, let's consider option C. If the products become more spread out, it implies an increase in disorder or randomness. When the individuals components of the system are more distributed, they have more possible arrangements, resulting in increased disorder. Therefore, option C is a possible answer.

Lastly, let's evaluate option D. If the products form fewer molecules, it suggests a decrease in the number of individual particles in the system. With fewer molecules, the number of different arrangements or configurations also reduces, leading to a decrease in disorder or randomness (entropy). Therefore, option D is incorrect.

Based on the explanations above, the correct answer is option C - The products becoming more spread out.