Final answer:
The legal blood alcohol limit in England of 350 µg of alcohol per 1 L of breath is equivalent to 350 ppb because 1 µg is equal to 1 ppb.
Step-by-step explanation:
In England, the legal blood alcohol limit is 350 µg of alcohol per 1 L of breath. To convert this concentration to parts per billion (ppb), you simply need to recognize that 1 g = 1 billion µg,
therefore 1 µg = 1 ppb. So, 350 µg/L is equivalent to 350 parts per billion (ppb) because there are 1 billion micrograms in a gram, which is what the 'per billion' part refers to.