Answer:
Mass of human head is 5,250 grams.
Step-by-step explanation:
Given the following data;
Body mass = 70kg
Mass of human head = 7.5% = 0.075
We simply multiply the body mass by that of the human head;
0.075 * 70 = 5.25kg
To convert the mass in kilograms to grams;
We know that, 1 kilogram = 1,000 gram.
Therefore,

5.25kg = 5,250 grams
Hence, the mass of human head is 5,250 grams.