A
nswer: -
C. Energy is released by the reaction
Explanation:-
An exothermic reaction is one in which during the progress of the reaction heat is evolved.
So energy is released by the reaction.
It cannot be created as energy is neither created nor destroyed as per the Law of conservation of energy. Energy is not transferred either.
The energy released during the progress of the reaction originates from the chemical bonds of the reactants as they break during their conversion into products.
I know what you're asking but I don't think the question is stated properly. Technically, an atom will not join with an "oxide" ion; i.e., the oxide ion is an atom of oxygen to which two electrons have been added. An oxide ion will add to 2 K ions or 1 Ca ion. The K ion has lost just one electron so it takes two of them to equal the 2- charge on the oxide ion whereas the Ca ion has lost two electrons and it takes only one of them to equal the charge on the oxide ion.
Answer: Concentration of the chemist's sodium chloride solution is 34.4 mol/L.
Explanation:
Molarity of a solution is defined as the number of moles of solute dissolved per Liter of the solution.
where,
n= moles of solute
= volume of solution in ml
Given : moles of 
= 6.89
volume of solution = 200 ml
Putting in the values we get:
Thus the concentration of the chemist's sodium chloride solution is 34.4 mol/L.
Answer:
A description of the experiment the chemicals were used for.
Explanation:
A chemical waste label is required to provide information about any hazardous waste present in the container. Some details are mandatory to mention of the chemical waste label to prevent any accident while doing the experiment, that includes:
- Chemical compound's name present in the container.
- Composition and physical state of the waste.
- Hazardous properties of the waste.
- The date of manufacturing.
- Amount of chemical compounds filled in the container.
A chemical waste label does not mention or describe the experiment for which the chemicals were used for, scientists, teacher or students should have knowledge of the chemical composition by reading their names and evaluate themselves on which chemical should be used for which experiment.
Hence, the correct answer is "A description of the experiment the chemicals were used for."
