In which of the following conditions would a person not hear an echo?
a. a sound wave reaches the ear, and the reflected wave reaches the ear less than 0.1 seconds later.
b. the reflecting source is approximately 21.5 meters from the person.
c. a person is standing 30 meters in front of the reflecting surface.
d. a person is standing in the range of the sound waves coming from the original sound source as well as the reflected waves.

1) in saturated limewater, [h+ ]=3.98x10-13 m. a) find [oh]-/ b) what is the ph? / c) is the solution acidic, basic, or neutral? / 2) in butter, [h+ ]=6.0x10-7 m. a) find [oh]-/ b) what is the ph? / c) is the solution acidic, basic, or neutral? / 3) in peaches, [oh]=3.16x10-11 m a) find [h+ ]/ b) what is the ph? / c) is the solution acidic, basic, or neutral? / 4) during the course of the day, human saliva varies between being acidic and basic. if [oh]=3.16x10-8 m, a) find [h+ ]/ b) what is the ph? / c) is the solution acidic, basic, or neutral? /

How many liters of ethylene glycol antifreeze (c2h6o2), with a density of 1.100 g/l, would you add to your car radiator containing 15.0 kg of water if you needed to protect your engine to - 21.5°c? for water, kf = 1.86°c m -1.

Volume is a measurement of how fast particles of a substance are moving