C.-6 16. What is the leading coefficient in the expression 2x2 - 4x2 + x4 - 6? a. 2 b. 1 17. What is the standard form of the given algebraic expression? 2x3 - 4x2 + x4 - 6 a. -6 - 4x2 + 2x3 + x4 b. 2x3 - 4x2 + x4 - 6 c. xt + 2x² – 4x² – 6 18-29. Convert the following. 18.8kg to g b. 800g c. 8000g a. 80g 19.850 mg tog b. 8.5 g c..859 a. 85g 20.370 g to mg c. 3.7 mg b. 3700 mg a. 37 mg 21-22.7.4 ha to m2 23-24. How many square meters are there in one square kilometre? c. 48 seconds b. 180 seconds 25. 3 minutes to seconds a. 300 seconds