Answer:
All energy is made by the sun because without the sun there would be no humans to produce other energy
Answer:
3
three half-filled orbitals each capable of forming a single covalent Bond and an additional lone - pair of electrons
Answer:
the sum of the numbers of protons and neutrons present in the nucleus of an atom.
The correct answer is D.
Echo refers to the sound that is heard when a sound wave is reflected back from a surface. An echo sound is made when a sound wave traveled through the air, hit a hard surface and get reflected back. Generally, hard surfaces reflect sound wave while soft surfaces absorb sound waves. Reflected sound waves are used in application of some devices that are used in range and direction finding.