Answer:
3.
Explanation:
Hello,
In this case, it is convenient to write the chemical reaction as:

Which balanced turns out:

Thus the number that should be in front of the calcium sulfate is 3 in order to balance the reaction.
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For the neutralization process: an acid acts as a donor and donates protons to the base. On the other hand, the base acts as an acceptor and accepts the transferred protons. In a nutshell, neutralization is mainly proton transfer process.
As for the redox process: the oxidized material usually transfers electrons to the reduced material. In a nutshell, redox is mainly electron transfer process.
Flammable liquid,gasoline, oil, and etc
During cellular respiration, the carbon and hydrogen atoms change partners and bond with oxygen atoms instead. The carbon-hydrogen bonds are replaced by carbon-oxygen and hydrogen-oxygen bonds. As the electrons of these bonds "fall" toward oxygen, energy is released.
Oxygen and Hydrogen would most likely form a covalent bond that is polar, or a polar covalent bond. Due to the electronegativity difference between the 2 elements, unequal sharing of the valence electrons will occur, electrons being in closer proximity to Oxygen and farther away from Hydrogen. Resulting in the characteristic partial positive and negative charges to appear for the respective elements.