a) Express 1400 ml as a percentage of 2.1 liters

First, we need to convert both volumes to the same unit. Let's convert liters to milliliters since 1 liter = 1000 milliliters.2.1 liters * 1000 ml/liter = 2100 mlNow we can express 1400 ml as a percentage of 2100 ml:(1400 ml / 2100 ml) * 100% = 66.67% (approximately)Therefore, 1400 ml is approximately **66.67%** of 2.1 liters.