The compound sodium carbonate is a strong electrolyte because it completely dissociates when placed in water into its component ions. The equation of the reaction can be expressed as:

The dissociation leads to the formation of sodium and carbonate ions with the latter held together by its internal covalent bond.
This is unlike weak electrolytes that do not dissociate completely in water or aqueous solutions. Only a small fraction of the solute exists as ions in the solution.
More on strong and weak electrolytes can be found here: brainly.com/question/3410548
Explanation:
The law of conservation of mass states that mass is conserved which also means that it cannot be created or destroyed within the isolated system.
We can add the mass of the reactant and can be equal to the mass of the product. But in some cases, it will not work like:
If reactants are not in the mole ratio, there will be a limiting reagent.
If a gas is one of reactants or products.
Radioactive decay and nuclear reactions(fission or fusion).
Answer:
C. All parts of Earth experience periods of daylight and darkness.
Explanation:
Not all parts of earth experience the same temperatures. For example, Alaska vs. Florida. Alaska is always freezing cold and Florida is generally always warm.
Not all parts of Earth experience extreme temperature changes either. For example, Florida doesn't experience extreme colds and Alaska doesn't experience extreme warmth.
Not all parts of Earth Experience the same amount of day and night. There are month long periods where Alaska doesn't see the sun, and it is pitch black, and dark. Florida experiences a decent amount of daylight. etc.
I used the same states for example throughout my answer to try to not confuse people. I hope my answer helped!