I believe the answer is 20 feet. According to McBurney and Collings, the average threshold of human hearing is the tick of a watch from 20 feet in very quiet condition.
The human hearing range is a description of the pitches and loudness levels a person can hear before feeling discomfort. There is a variety of sounds in our environment, ranging from faint sounds like birdsong and rustling leaves to louder sounds like music, yelling, and industrial noise.
Answer:
C
Explanation:
Atoms share electrons. Electrons are simultaneously attracted by the two atomic nuclei. A covalent bond forms when the electronegativities of the atoms are too small for the transfer of electrons (to form ions).
Answer:
Food chains show a single path of energy in an ecosystem, and food webs show all the overlapping food chains in that ecosystem. Food webs show the path of energy in an ecosystem, and food chains show the path of nutrients in that ecosystem
Explanation:
Answer:
c. This statement is true because plants are able to convert sun energy into food energy and animals must get their energy from plants or other organisms that eat plants.
Explanation:
Green plants are autotrophs. They synthesize their food in the presence of sunlight, using carbon dioxide gas and water. Whereas animals are heterotrophs, they cannot make their food but use food prepared by green plants. Thus, plants are able to convert sun energy into food energy and animals must get their energy from plants or other organisms that eat plants. The statement is true.
Answer: New species appear as a result of big changes over a short period of time
Explanation: