Answer:
1,8066 x 1024 atoms
Explanation:
1 mole of chromium contains 6,022 x 1023 atoms
so
3 moles of chromium contains 3 times as many atoms
3 x 6,022 x 1023 = 1,8 066 x 1024
Electromagnetic waves can travel in vaccum but mechanical wave does not
1250 decigrams
1 gram = 10 decigrams
To solve this problem it is necessary to apply the concepts related to Dopler's Law. Dopler describes the change in frequency of a wave in relation to that of an observer who is in motion relative to the Source of the Wave.
It can be described as

c = Propagation speed of waves in the medium
= Speed of the receiver relative to the medium
= Speed of the source relative to the medium
Frequency emited by the source
The sign depends on whether the receiver or the source approach or move away from each other.
Our values are given by,
Velocity of car
velocity of motor
Velocity of sound
Frequency emited by the source
Replacing we have that



Therefore the frequency that hear the motorcyclist is 601.7Hz
Answer:
31
Explanation:
Given:
U=3
X=4
Y=7
u + xy
Substitute the given values to the equation:
3 + (4)(7)
3 + 28
31