Answer
• Improving the environmental performances
• Developing Green Mining technology
Explanation
The effect to the environment caused by opal mining are; impact on soils and geology, clearing of native vegetation disrupting flora and fauna, change in land use and effects of air quality.
Opal mining is currently examining environmental impacts and adopting measures that mitigate the impacts making the process less destructive to the environment.
With the current commitment to sustainability, opal companies are investing funds for Green Mining as a positive way to impact the environment before and after mining.
The correct answer is circular. Copernicus and other astronomers before him thought that celestial bodies followed a circular orbital path. Copernicus was a Polish astronomer that concluded that the sun is at rest near the center of the universe and the earth is revolving around it annually. This theory is called heliocentric.
Answer:

Explanation:
The force is defined as the negative of the derivative of the potential energy:

If we use the potential energy function given in this problem:

and we calculate the force, we get:

So, the force is

Twenty is the atomic number of potassium.