How many bonds does silicon tetrachloride, SiCl4 have?

Neils bohr believed that electrons orbited the nucleus in different energy levels, based on strong support from

Use examples from the article to explain one positive and one negative effect that chemistry has had on society.

About 3% of the water on earth is freshest. only about 40% of that freshwater is available for human use. why is so much freshwater unavailable for human use?