Determine the pH of 0.050 M HCN solution. HCN is a weak acid with a Ka equal to 4.9 × 10-10.

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.

the correct answer would be b) volume versus temperature, because they are also directly proportional.