How can you tell which isotope is the most common?

Miner's coal distributors does not mine coal itself, nor does it even store or handle the coal. instead, miner's solicits orders for low sulfur coal from other firms, then purchases the required amount from suppliers and directs them to ship the coal to its customers. what is miner's

Which statement describes the phase change that occurs when dry ice is placed in an open container at room temperature?

Ab c or d ? i’m not sure what the answer is