Lars observes a substance to be a solid and to float in water at room temperature (23°C). Based on the given properties, which substance is the most likely identity of this sample? Substance Melting Point (°C) Boiling Point (°C) Density at Room Temperature (g/cm3)
carbon tetrachloride -22.9 76.7 1.59
cetyl alcohol 49.3 344 0.811
dichlorobenzene 53.5 174 1.25
sulfur hexafluoride -64 -50.8 0.00617
A.
carbon tetrachloride
B.
cetyl alcohol
C.
dichlorobenzene
D.
sulfur hexafluoride

D. Sulfur Hexafluride

Explanation:

I hope this helped !!

first let us lay out the formula for potential

and kinetic energy:

pe = mgh

ke = (mv^2)/2

where: m=mass, v=velocity, g=gravitational

acceleration, h=height

calculating for mass using the known values of

pe:

340j = m (9.81 m/s^2) (50ft) (1m/3.28ft)

m = 2.27 kg

the law of conservation of energy states that

energy is neither created nor destroyed. therefore, the change in kinetic

energy from 50 ft to 35 ft would be equal to the change in potential energy

from 50 ft to 35 ft. however it would be opposite in signs since one is losing

while other is gaining.

ke(35ft) – ke(50ft) = - [ pe(35ft) – pe(50ft]

ke(50ft) = 0 since the brick is initially at rest

ke(35ft) = 340j - 2.27kg (9.81 m/s^2) (35ft)

(1m/3.28 ft)

ke(35ft)

= 102.38 j