An unknown substance has a mass of 15.5 g . When the substance absorbs 1.395×102 J of heat, the temperature of the substance is raised from 25.0 ∘C to 45.0 ∘C . What is the most likely identity of the substance?

iron (Fe)

Explanation:

Use q = mcΔT.

q = 1.396 x 10^2 J

m = 15.5g

ΔT = (45.0 - 25.0) = 20 degrees celcius

1.396 x 10^2 = 15.5 x c x 20

c = .450 J/g x degrees celcius

This is closest to the specific heat of iron/steel.

nacl is added to the aqueous of what? ? in order to get a proper answer you have to specify the exact composition of the aqueous solution.

in scientific notation, the value of the  speed of light in a vacuum

  will be written as 2.995 * 10^8. when this value is represented in the form of

  a * 10^b, then, a = 2.995 and b = 8.

the value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. in this case, the scientific notation will be written as 3 *10^8.