Calculate the number of atoms in 3 mol helium

1.81 x 10²⁴ atoms He

Explanation:

You can find the amount of atoms by multiplying the given moles by Avogadro's Number. This number represents the amount of atoms per 1 mole. It is important to arrange the ratio in a way that allows for the cancellation of units.

Avogadro's Number:

6.022 x 10²³ atoms = 1 mole

3 moles He           6.022 x 10²³ atoms
 x    =  1.81 x 10²⁴ atoms He
                                       1 mole

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

a is the correct answer