You will know the ones. Pick the word whose underlined sound differs from the rest. You were confident, then you checked the key and you were wrong, and the correct answer left you staring at the page.
This is a common experience for English learners, and there is a reason for it. English vocabulary is vast, and there are plenty of words we have quietly been mispronouncing for years. Exam writers know exactly which ones those are, and they use them.
When students ask me how to know how a given word is pronounced, or whether there is a method for spotting the odd one out, my honest answer is that there is not. This falls squarely into the category of read more, listen more, learn more, know more. It accumulates slowly, over a long time, until your instinct for it is reliable.
A student raised exactly this with me the other day, and my answer was the same. With language, it is patience and repetition that gets you there.