Ultrasonic waves a. are painful to the human ear b. are sound waves with frequencies below 20 hz c. can be used to see internal organs d. travel most quickly through gases need

C. can be used to see internal organs

Explanation:

Ultrasonic waves can provide details of internal structures of organs, fetuses and even blood circulation in real time and without causing tissue damage. The ultrasound device emits sounds of very high frequencies, between 2 MHz and 10 MHz (megaHertz), which are produced by a transducer. The transducer consists of a small piezoelectric crystal, capable of producing a small electrical current when it undergoes vibration. In this way, when the transducer crystal captures an echo of a sound wave that was reflected by some structure below the skin, a small electrical signal is produced and translated by the computer in the form of an image.

Although safe, non-ionizing, ultrasonic waves can cause small biological effects. During their propagation in the human body, ultrasonic waves transfer energy to the tissues, heating them and producing free radicals, which can cause damage to the genetic code of cells.

i do not know and i have a 100 in this class

4.) metal

"-the movement of carbon from the nonliving environment into living things and back to the environment

-carbon is the essential component of proteins, fats, and carbohydrates (which make up all organisms)

-carbon exists in air, water, and living organisms

-producers convert carbon dioxide in the atmosphere into carbohydrates during photosynthesis

-bacteria in the atmosphere cycles through the system in filtration units

-in cellular respiration, carbon is released back into the atmosphere as carbon dioxide

-some carbon is stored in limestone (forming one of the largest "carbon sinks" on earth)

-largest carbon reservoir on earth= limestone

-carbon stored in the bodies of organisms as fat, oils, or other molecules may be released into the soil or air when the organism dies

-this may form deposits of coal, oil, or natural gas (fossil fuels, which increased the atmospheric carbon dioxide)

-fossil fuels store carbon left over from bodies of organisms that died millions of years ago

-they are located in the surface of earth, deep within the earth and beneath the ocean floor."