Does the element protactinium have stable isotopes.

Protactinium has no stable isotopes.

Explanation:

Isotopes: Protactinium has 27 isotopes whose half-lives are known, with mass numbers 212 to 238. Protactinium has no stable isotopes. Its longest lived isotopes are 231Pa, with a half-life of 32,760 years, 233Pa with a half-life of 26.967 days and 230Pa with a half-life of 17.4 days.

(i used this website: https://www.chemicool.com/elements/protactinium.html )

c is the answer because when something is left after something evaporates that shows the chemical change.

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