4al + 3o2 → 2al2o3 what does the "3" in front of o2 stand for? a) it indicates that there are 5 oxygen atoms after you add the coefficient and the subscript. b) it indicates that that there are are total of 6 oxygen atoms all bonded together as a single molecule. c) it indicates that there are 3 oxygen molecules chemically bonded to each other in the reaction. d) it indicates that there are 3 separate oxygen molecules in the reaction.

the right choice is D) It indicates that there are 3 separate oxygen molecules in the reaction.

HOPE I HELPED :)

- It indicates that there are 3 separate oxygen molecules in the reaction.

Explanations:- is oxygen molecule in which two O atoms are bonded together with a double bond(O=O). The numbers written in front of the chemical formulas in an equation are the coefficients and they are used to balance the equations.

The balanced equation has 3 molecules of and all these molecules are separate from each other as the bonds are between two oxygen atoms of a molecule but not between the oxygens of two molecules.

Of course there are 6 oxygen atoms in total but they all are not bonded together as a single molecule.

So, the right choice is D) It indicates that there are 3 separate oxygen molecules in the reaction.

- decrease the number of plants and animals living in the water.

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."