Answer:
Historically, wood was the main source of U.S. energy until the mid-1800s and was the only commercial-scale renewable source of energy in the United States until the first hydropower plants began producing electricity in the 1880s.
The Advantages of Renewable Energy Resources-A Fuel Supply That Never Runs Out.Zero Carbon Emissions.Cleaner Air and Water.Disadvantages of Renewable Energy-he Electricity Generation Capacity is Still Not Large Enough.Renewable Energy Can be Unreliable.
First, we need to take advantage of the world's abundant natural gas resources and reduce coal consumption;
Second, governments must support development of carbon capture and storage technology to make fossil fuel use cleaner;
Explanation:
Answer:
Boron has 3 valence electrons
For the first question, salt is soluble while sand is insoluble or not dissolvable in water. The salt should have vanished or melted, but the sand stayed noticeable or visible, making a dark brown solution probably with some sand particles caught on the walls of the container when the boiling water was put in to the mixture of salt and sand. The solubility of a chemical can be disturbed by temperature, and in the case of salt in water, the hot temperature of the boiling water enhanced the salt's capability to melt in it.
For the second question, the melted or dissolved salt should have easily made its way through the filter paper and into the second container, while the undissolved and muddy sand particles is caught on the filter paper. The size of the pores of the filter paper didn’t change. On the contrary, the size of the salt became smaller because it has been dissolved which is also the reason why it was able to go through the filter paper, while the size of the sand may have doubled or even tripled which made it harder to pass through.
