1s²
Explanation:
The predicted electron configuration of Helium 1s².
Helium is an element with atomic number of 2. it is located on the last group on the periodic table.
- Electron distribution into the energy levels or sublevels of atoms can be shown using electronic configurations.
Here, the two electrons in Helium fills the first energy level with s-sublevel first.
The maximum number of electrons in the sub-level is 2: this gives the 1s² configuration.
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The answer to this problem is =12
Answer:
atoms of 40K
Explanation:
You can use the molecular mass and the Avogadro´s number, in the following formula:
where 
is the sample mass, 
is the molecular mass of the KCl and IA(40K) is the isotopic abundance of 40K.
Now replacing the values, you can find:
Answer:
This question is incomplete, the remaining part of the question is:
What is the control group, independent variable and dependent variable?
Control group: Plants placed in 80 degree rooms
Independent variable: Change in temperature
Dependent variable: Change in color of leaves
Explanation:
The independent variable in a scientific experiment is the variable that the experimenter controls or manipulates in order to bring about a change in the dependent variable. In this experiment, the variable manipulated by Justin B is the TEMPERATURE CHANGE.
On the other hand, a variable is said to be dependent if it is the variable that responds to a change made to the independent variable or rather it is the outcome. In this experiment, Justin B is trying to see the outcome on the color change in leaves when exposed to a low temperature, hence, COLOR CHANGE IN LEAVES is the dependent variable.
Control group of an experiment is the group that receives no experimental treatment. It is the group the experimenter considers normal and hence is comparing with his experimental group. In this experiment, Justin B believes the leaves change color in a low temperature, hence, he placed some plants in a lower temperature (60 degree) in order to compare them with when the plants are placed in a higher temperature (80 degree). As far as this experiment is concerned, the plants placed in 80 degrees temperature are believed by Justin B not to undergo color change, hence, they are the CONTROL GROUP while the group he placed in 60 degrees temperature are what he is interested in, making them the EXPERIMENTAL GROUP
Each orbital must contain a single electron before any orbital contains two electrons.
