Answer:
He developed the concept of concentric electron energy levels
Explanation:
Before Bohr's model, Rutherford's model was proposed. This model explains most of the properties of the atom but failed to explain the stability of the atom.
As per Rutherford's model, electrons revolve around the nucleus in the orbit.
But revolving electron in their orbit around nucleus would give up energy and so gradually move towards the nucleus and therefore, eventually collapse.
Bohr's proposed that the electrons around the nucleus move orbit of fixed energy called "stationary states". Electrons in these stationary states do not radiate energy.
Therefore, proposal of concentric electron energy levels refine the atomic models.
The answer is 40.
We can solve this by finding out the number of protons, and neutrons. Atomic number of an element means the number of protons in that element. So, the atom has 30 protons if the atomic number is 30.
On the other hand, mass number is the total number of protons and neutrons, but not electrons, because they're too light comparing to the other 2. Therefore, we can simply solve the number of neutrons in the atom by subtracting the number of protons from the mass number. 70 - 30 = 40.
Therfore, the number of neutrons is 40.
The correct order given below shows the changes that occurs in a mice population in response to changes in their environment:
- The population of mice is in an environment with many black rocks
- Mice with black for are more likely to survive and reproduce than mice with brown fur
- After many generations, most of the mice in the population have black fur
- A sandstorm covers most of the population's environment with brown sand
- Mice with black fur are less likely to survive and reproduce than mice with brown fur
- After many generations, most of the mice in the population have brown fur
<h3>What is the correct order for natural selection in the desert environment given?</h3>
Based on the process of natural selection due to envrionmental pressures, the population of the mice in the desert changes as follows before and after the environmental change:
- The population of mice is in an environment with many black rocks
- Mice with black for are more likely to survive and reproduce than mice with brown fur
- After many generations, most of the mice in the population have black fur
- A sandstorm covers most of the population's environment with brown sand
- Mice with black fur are less likely to survive and reproduce than mice with brown fur
- After many generations, most of the mice in the population have brown fur
Therefore, the correct order shows the changes that occurs in a mice population in response to changes in their environment.
Learn more about about adaptation at: brainly.com/question/25594630
Answer:
w = -531 kJ
1. Work was done by the system.
Explanation:
Step 1: Given data
- Heat gained by the system (q): 687 kJ (By convention, when the system absorbs heat, q > 0).
- Change in the internal energy of the system (ΔU°): 156 kJ
Step 2: Calculate the work done (w)
We will use the following expression.
ΔU° = q + w
w = ΔU° - q
w = 156 kJ - 687 kJ
w = -531 kJ
By convention, when w < 0, work is done by the system on the surroundings.
40×19.32/100=7.7=8×2=16Ca
35.5×34.30/100=12.1=12×2=24Cl
16×46.38/100=7.4=7×2=14O
