Answer:
The answer to your question is: B and C.
Explanation:
Neon atomic number = 10
Electron configuration is not : 1s²2s¹2p⁶ .
This electron configuration is for fluor (9 electrons) because is we sum up the electrons ( 2 + 1 + 6) the result is 9.
A)The 3s orbital should be part of the configuration. This is not the right reason.
B)The total number of electrons is incorrect. This correct, the number of electrons is 9 instead of 10.
C)The 2s orbital does not have enough electrons. This option is correct, 2s must have 2 electrons and it only has 1.
D) The 1s orbital does not have enough electrons. This option is incorrect, 1s orbital can have only 2 electrons.
They did not repeat their tests multiple times.
Reason being is using the same stopwatch doesn’t matter and changing the reactants won’t help, and you without a doubt need more than one person collecting the data so,
They did not repeat their tests multiple times is the answer.
Answer:

Explanation:
Potassium nitrate is a soluble salt which readily dissolves in a polar solvent, such as water. When solid potassium nitrate is dissolved in water, it dissociates into potassium cations and nitrate anions.
Due to the resultant ionic charges, the polar water molecules attract the resultant ions and potassium nitrate ions become hydrated, that is, surrounded by water molecules.
Nitrate, our anion, attracts the partially positive ends of water molecules by attracting them via hydrogen atom.
Potassium, the cation, attracts the partially negative end of water molecules by attracting via oxygen atom.
Answer: exothermic
EXPLANATION: any process in which heat energy is released is called an exothermic process. For example burning of wood produces heat, so combustion of wood is an exothermic process.
When chemicals were not mixed they were at room temperature and when we mix them exothermic reaction took place and heat was released which raised the temperature of mixture.
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