Consider the general reversible reaction. Lower a upper a plus lower b upper b double-headed arrow lower c upper c plus lower d upper d. What is the equilibrium constant expression for the given system?.

B. 40 to 140 psi
u can calculate wid the formulas taught

It depends on the subject for me. some exams are easier than others so i usually go through it and answer questions i know based on my general knowledge, then double check after. going through the lesson can a lot  because the exams can be  very lesson-specific, but sometimes they are ridiculously long so a lot of people don't take the time. i did find that, when i went through the lessons, i was making 100's on my exams vs strictly using + the internet and  i make 90's. 

Frequency is the number of complete oscillations of a wave per second.