<u>Answer:</u>
The correct answer option is a. Selenium (Se).
<u>Explanation:</u>
From the given answer options, Selenium (Se) is the only element which is a non metal.
It has the atomic number 34 with atomic weight 78.96. It is a member of the sulfur group of the non metallic elements and falls in period 4 of the Periodic table.
Selenium has non metallic properties which are intermediate between the elements that lie above and below it in the Periodic table.
Answer: Option b. 50 neutrons and 38 protons.
Explanation:
Atomic number = proton number = 38
Mass number = proton number + Neutron
Mass number = 88
Proton = 38
Neutron number =?
Neutron number = Mass number — proton number
Neutron number = 88 —38 = 50
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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CuBr2 is the formula for copper ii bromide.
