Students can use to distinguish pure substances, such as elements and compounds with a constant composition, from other substances. a) color b) density c) particle size d) state of matter

Answer is: B) density.

Pure substance is made of only one type of atom or only one type of molecule, it has definite and constant composition with distinct chemical properties.

Mixtures are physical combinations of pure substances that have no definite or constant composition.

With constant composition density of pure substance is always the same and in other substances it can vary according the composition.

Density is a measure of mass per unit of volume.

The SI derived unit for density is the kilogram/cubic meter, but chemist usually use gram per cubic centimeter.

ur answer would be b hope i let me know if it is right

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