What are the conditions necessary to produce a reservoir for petroleum or natural gas?

The a metal retainer that keeps the rolling elements evenly spaced. n a. seal n b. separator n c. bearing n d outer race

Which of the following is the largest disadvantage of about half of the electricity in the united states comes from burning

Atoms seldom exist as independent particles in nature a) as single particles, most atoms have low potential energy b) their electronegativity is much lower when they combine with other atoms c) atoms are more stable when they combine with other atoms d) neutral particles are rare