Answer: The values that have exactly three significant figures are,
0.0230, 0.804, 140 and 509
Explanation:
Significant numbers or significant number is a number that is used to express the value of the number.
In 0.0230 grams, there are three significant figures,
In 0.035 ounces, there are 2 significant figures,
In 0.804 inches, there are 3 significant figures,
In 3.150 liters, there are 4 significant figures,
In 140 feet, there are 3 significant figures,
in 509 km, there are 3 significant figures.