Since your problem doesn't suggest a salinity level, we'll assume this calculation is for pure water.
Volume is measured in cubic centimeters, or cm3.
1g of water at 20°C is 0.9982cm3, so to find the volume of 998g we can do some simple multiplication:
- 998 * 0.9982 = 996.2036
So 998g of water at 20°C fills a volume of 996.2036cm3.
Had the water been 4°C the calculation would have been even easier as 1g is equal to exactly 1cm3, so 998g is 998cm3.
As a bonus tip, here's a calculator that will convert grams per cubic centimeter to pounds per cubic inch.
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