If I had COPD or asthma will it show on a chest x ray?

No... Neither COPD nor asthma is diagnosed by x-ray but other diseases can be ruled out by getting a chest x-ray, like pneumonia, congestive heart failure, pneumothorax, etc.
Sometimes. We do not diagnose asthma or COPD by x-rays or ct scans. That being said, we do commonly see evidence of emphysema on ct scans. We diagnose these breathing disorders with a pulmonary function test.