Give an example for each of the four basic substances of a cell (carbogydrates, proteins, lipids, and nucleic acids)

Carbohydrates are the sugars, starches and fibers found in fruits, grains, vegetables and milk products

proteins are meats.

Lipids are a group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), monoglycerides, diglycerides, triglycerides, phospholipids, and others.

nucleic acids are complex organic substance present in living cells, especially DNA or RNA, whose molecules consist of many nucleotides linked in a long chain.

The density of water is 1 g/cm cubed and in order for the pebble to sink its density has to be greater than the density of water and in order for the twig to float its density has to be less than the density of water

"electrical energy" transforms to "thermal energy".hope my answer has you : )