Which was a testable idea that j. j. thomson developed through his experiments?

atoms are the most important substances in the universe.
it is impossible to divide an atom into smaller parts.
there are electrically neutral particles inside atoms.
atoms contain small, negatively charged particles.

The correct statement is atoms contain small, negatively charged particles.

Explanation:

J.J.Thomson was a scientist which discovered electrons that are present in an atom.

He did an experiment and gave a model for this. The experiment conducted by him was Cathode Ray experiment and the model given by him was Plum pudding model.

From cathode ray, he showed that the cathode ray was composed of a negatively charged particles and named it as electrons. From plum pudding experiment, he said that the electrons are embedded in the atom. These particles carry negative charge and are very small as compared to the atom.

Hence, the correct statement is atoms contain small, negatively charged particles.

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

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.