The question, as stated, cannot be answered sensibly. A cubic centimetre per hour is a measure of volume per hour, with dimensions [L3T-1]. A microgram is a measure of mass, with dimensions [M]. The two measure different things and elementary dimensional analysis teaches that you cannot convert between measures with different dimensions such as these without additional information. Althernatively, a microgram per hour is a measure of mass per hour with dimensions [MT-1] but the rest of the argument remains unchanged.
As a simple mental exercise consider a cc of air and of water. They will have very different masses.
1000 mg per gram
100mg = 100,000 micrograms (1000mcg per mg).
(542 mg) / (1,000 mg per gram) = 0.542 gram
12mg equals 12000mcg (1000mcg per mg).
0.25mg equates to 250mcg (1000mcg per mg).
620 (mg per liter) = 62 mg per deciliter.
There are 109 mg per dL.
There are 1,000 micrograms in 1 milligram.
about 148 mg per grapefruit.
0.1cg per milligram.
10200mcg (1000mcg per mg).
One dram is 3,888 mg
1.5mg (1000mcg per mg).
400mcg (1000mcg per mg).
1000 mg per gram
250000mcg (1000mcg per mg).
No, 300 mg per cc does not equal 25 mg per kg. To convert 300 mg per cc to mg per kg, you need to know the weight of the individual in kg. If you're looking for a general conversion, you would typically need to know the volume of the substance in cc and the weight of the individual in kg to determine how many mg per kg 300 mg per cc would be.