The speed of sound in air is approximately 350 m/s. You are sitting in a canyon with cliffs 525 m from you. You clap your hands. How long a delay is it to hear an echo of the clap?

3 s.

Explanation:

Echo is defined as the repetition of a sound produced by the reflection of sound waves from an obstructing surface like a wall, mountain etc.

v = f*lambda

Where,

Lambda = wavelength of the wave

f = frequency of the wave = 1/t

v = velocity of the wave.

Distance there and back = initial ditance * 2

= 525 x 2

= 1050.

Time taken, t = lamda/velocity

= 1050 / 350

= 3 s.

So the delay is 3 seconds.

answer;

d. are made mostly of liquid

explanation;

-the general   composition and structure planets includes; they have a thick gas and liquid layer covering a small,solid core. mostly the gases are hydrogen and helium atmosphere and layers of liquid hydrogen. for instance neptune and uranus are examples of the outer planets, they have a core covered by ice and ammonia.

-neptune's atmosphere is hydrogen and helium with a bit of methane so there is no oxygen to breath and the interior is made up of frozen water and ammonia with a rock and iron core. thus, there is no liquid water or solid surface to survive.