An echo is an example of the type of wave interaction called

Explanation:

There are many types of wave interactions i.e. reflection, refraction, diffraction, interference etc.

An echo is an example of the type of wave interaction called reflection. It follows the laws of reflection. A sound wave strikes a surface, it strikes the surface and reflect back producing repeated sound called echo.  

Hence, echo is an example of reflection of sound.

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.

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