The Earth's gravitational force accelerates objects when they fall. It constantly pulls, and the objects constantly speed up.
The relation between density, mass and volume is

1) to calculate = volume
given:
Density = 0.0915 g/ mL
mass = 17.7 grams
formula used:

Thus
Volume 
Answer: 193.44 mL
2) the mass of sample will be

Answer: 7 g
When a non metal gains or share by two electrons then the valency will be 2^- or 2^+
Answer: this relationship would be mutualism
Explanation: it is a relationship where both species benefit