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.
<span>B. Hydrogen is electrically neutralized in the solution. Hydrogen is a chemical element with symbol H and atomic number 1. With a standard atomic weight of circa 1.008, hydrogen is the lightest element on the periodic table.</span>
(P1V1/T1)=(P2V2/T2)
I just took the test and this should be correct
Answer: (D) Are there solvents mixed in (or is it water based)?
