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

answer: 802.3 kilo joules of energy represents 191.75 kilo calorie of energy.

explanation:

energy released during combustion of one mole methane = 802.3 kilo joules

if 1 kilo joule = 0.239006   kilo calorie

then ,802.3 kilo joule will be = 802.30.239006 kilo calorie

802.3 kilo joule = 191.75 kilo calorie

hence, the energy in kilo calorie is 191.75 kilo calorie.

total distance/total time

(85 + 82)/(5+3)

167/8

20 just over

0 = 0.40 / 0 = 0

= 0.20 = 9.80 ⁄2 =?

=0 , = = 0.20 =0.50 0 0.40 ⁄

=0−122 =0−12(9.80 ⁄2)(0.50)2 =1.2

a. carbon monoxide from car exhaust

b.particulate matter, such as soot

c.water vapor from a factory smokestack

d.acid rain

these are the answer choices im on that question right now