Answer:
Option c: Possible electron energy states are quantized within an atom.
Explanation:
The Bohr's Model of the hydrogen atom consisted of the movements of the electrons around the positively-charged nucleus in circular orbits that have a certain energy state. The energy of that orbit is given by:

<em>Where:</em>
E(n): is the energy of an electron in a particular orbit
R: is the Rydberg constant
h: is the Plank constant
c: is the speed of light
n: is a positive integer which corresponds to the number of the orbit
The ground state energy of a electron in the hydrogen atom is equal to -13,6 eV.
Bohr's Model aims to propose that the electron is restrictedly to occupy a certain region in the atom.
Therefore, the conclusion of Bohr after observing emission spectrum lines is that "possible electron energy states are quantized within an atom", so the correct option is c.
I hope it helps you!
Six elemental gases are composed of such exceptionally stable atoms that they almost never react with other elements. They are the gases that make up Group 0 (the rightmost column) of the periodic table: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn).
Answer:
0.1066 hours
Explanation:
A common pesticide degrades in a first-order process with a rate constant (k) of 6.5 1/hours. We can calculate its half-life (t1/2), that is, the times that it takes for its concentration to be halved, using the following expression.
t1/2 = ln2/k
t1/2 = ln2/6.5 h⁻¹
t1/2 = 0.1066 h
The half-life of the pesticide is 0.1066 hours.