a) m = 3820 g = 3.820 kg
b) m = 0.823 kg = 823 g
c) d = 450 um = 450000 mm
d) c = 133 m/s = 133*3.6 km/h = 478.8 km/h
e) A = 240 cm² = 2.40 dm²
f) V = 25 dm³ = 0.025 m³
g) n = 0.280 kmol = n = 0.000280 mol
h) v = 80 km/h = 80/3.6 m/s = 22.22 m/s
i) v = 10 km/min = 10 * 1000/60 m/s = 166.7 m/s
j) v = 300 m/s = 300 * 60/1000 km/min = 18 km/min
k) v = 30 m/s = 30*3.6 km/h = 108 km/h
l) v = 30 mm/s = 30 * 60/1000 m/min = 1.8 m/min