Sound intensity is inversely proportional to the square of the distance between the source and the receiver.
That is
I = k/r^2
where
k = constant
r = radius
When r=1, the intensity is I₁ = k/1 = k
When r=3, the intensity I₂ = k/3² = k/9
Therefore
I₂ = I₁ /9
In decibels,
I = 10 log₁₀(I/I₀)
where I₀ = reference intensity
When r=1,
10 log₁₀ (I₁/I₀) = 270
When r =3,
10 log₁₀ (I₂/I₀) = 10 log₁₀ [(I₂/I₁)*(I₁/I₀)]
= 10 log₁₀ [(1/9)*(I₁/I₀)]
= 10 log₁₀(1/9) + 270
= 260.5
Answer: 260.5 dB (nearest tenth)
This reaction is unbalanced. If you balance it, it would be:
2Al + 6HCl --> 3H2 + 2AlCl3
That way there are two aluminums on each side, six hydrogens on each side, and six chlorines on each side.
The answer is C, A CD-ROM is a compact disk that contains stored
information that can be read on a computer. which can be used and store
for a long time. A CD-ROM store data in digital format. data is written
from a laser light on the disk. Minimum capacity this drive is around
700 MB.
