<u>Answer:</u> The mass of osmium in kilograms and in pounds are 318.9141 kg and 703.085 pounds.
<u>Explanation:</u>
To calculate the volume of sphere, we use the formula:

where,
r = radius of sphere
We are given:
Radius of osmium = 15 cm
Volume of osmium = 
Density of osmium = 
To calculate mass of a substance, we use the equation:

Putting values in above equation, we get:

To convert the given mass into kilo grams and pounds, we use the conversion factors:
1 kg = 1000 grams
So, 
And,
1 pound = 453.592 g
So, 
Hence, the mass of osmium in kilograms and in pounds are 318.9141 kg and 703.085 pounds.