Weathering and chemical substance weathering
Answer:
D or A
<em>But I do know...</em>
It's because new strains of the virus are constantly appearing and evolving, so the vaccine must change along with them.
Chemical reaction can be reversed if the energy of the reactants is less than the activation energy threshold.
<h3>
What is a reversible reaction?</h3>
A reversible reaction is a reaction in which the conversion of reactants to products and the conversion of products to reactants occur simultaneously.
<h3>Conditions for reversible reaction</h3>
In equilibrium reaction, the activation energy of the forward reaction is more than that of backward reaction which causes bond breakage of the reactants.
Activation energy = (Threshold energy) - (Internal energy of the reactants)
Thus, a chemical reaction can be reversed if the energy of the reactants is less than the activation energy threshold.
Learn more about reversible reaction here: brainly.com/question/16614855
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Dwarfs - A
Giants - C
Main Sequence Stars - B
Supergiants - D
Answer: The products of electrolysis are Zn(l) and 
gas
Explanation:
Electrolysis of a subastance is breaking it into its constituents by the action of electrical current.
In the electrolysis of molten zinc chloride, zinc metal is produced at the cathode which is a negative electrode and chlorine gas produces as the anode which is a positive electrode.
At anode : 
At cathode : 
