Explanation:
Atomic number of hydrogen is 1 and its electronic configuration is 
. So, in order to attain stability it needs to gain one more electron from another atom.
As helium cannot donate its one valence electron because if it does so then there will be no electron present in a hydrogen atom which is not possible. Therefore, it needs to share its valence electron with another atom.
A chemical bond formed by sharing of electrons is known as a covalent bond. So, hydrogen atom always shares its valence electron and hence, it always forms a covalent bond.
On the other hand, atomic number of helium is 2 and its electronic configuration is 
.
Since, helium atom has completely fill orbital so, it is stable in nature. Therefore, it will neither gain or lose electrons under normal conditions.
As a result, helium will not form a covalent bond.
An increase in the temperature will speed up the reaction by increasing the frequency and efficiency of the collisions of molecules.
Answer:
b) It produces electrical current spontaneously.
Explanation:
Cells capable of converting chemical energy to electrical energy and vice versa are termed Electrochemical cells. There are two types of electrochemical cells viz: Galvanic or Voltaic cells and Electrolytic cells. Voltaic cell is an elctrochemical cell capable of generating electrical energy from the chemical reaction occuring in it.
The voltaic cell uses spontaneous reduction-oxidation (redox) reactions to generate ions in a half cell that causes electric currents to flow. An half cell is a part of the galvanic cell where either oxidation or reduction reaction is taking place. Hence, the spontaneous production of electric currents is true about Voltaic/Galvanic cells.
The statement that identifies an oxidation-reduction reaction is a reaction in which oxidation numbers change (option C).
<h3>What is a redox reaction?</h3>
A redox or oxidation-reduction reaction is a chemical reaction in which some of the atoms have their oxidation number changed.
In a chemical reaction that involves oxidation and reduction, the oxidation number of the involved ions either decreases or increases.
Therefore, the statement that identifies an oxidation-reduction reaction is a reaction in which oxidation numbers change.
Learn more about redox reaction at: brainly.com/question/13293425
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ADSORPTION: The adhesion of a liquid or gas on the surface of a solid material, forming a thin film on the surface. Not to be confused with the process of absorption.
ABSORPTION: The act or process of absorbing or of being absorbed as
