Each period represents once a principal energy level has been reached for an element.
Answer:
B
Explanation:
The student is not able to move the box in D --> 55N, 0N. Since the net force is 0, it means that no force is being applied. So you will choose answer B from your options.
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Answer:
It can create a new plant variety, cure diseases or like the current epidemic situation, vaccines, drugs, ...
Explanation:
<u>Answer:</u> This violates the law of constant composition.
<u>Explanation:</u>
Dalton's theory is based on mainly two laws, which are law of conservation of mass and law of constant composition.
Law of constant composition states that a compound always contain the elements in the fixed ratio by their masses.
For Example: In water 
, the hydrogen and oxygen are present in the fixed ratio of 1 : 9 by their mass.
We are given:
A sample of titanium dioxide having 59.95 % of titanium and another sample of titanium dioxide having 60.10 % of titanium.
As, the compound is titanium dioxide. So, the mass percent of titanium must remain the same in both the elements.
Hence, this violates the law of constant composition.
Answer: E. Occurs when methane gas is burned.
Explanation:
A chemical change occurs when matter undergoes a change to form a new substance with different chemical properties, and the reaction is usually not reversible.
In the case of burning methane gas (CH4) ,oxygen and methane are the reactants, while the new substance formed from the reaction are carbondioxide (CO2) and water (H2O) .
