B.
The cynobacteria were already there without the oxygen, so that rules out A, and a lot of prokaryotes were anaerobic, so that rules out C. Finally, Photosynthesis does not require oxygen. Instead, Oxygen is a waste product of it. Therefore, it cannot be D. So, we are only left with B
Hoped this helped :D
pH value 1 represents a solution with the lowest OH⁻ion concentration.
<u>Explanation:</u>
pH is given by the expression as the negative logarithm to the base 10 of the concentration of hydrogen ions.
pH = -log₁₀[H⁺]
If the pH is lower than 7, pH < 7 then it is acidic
If the pH = 7, then it is neutral
If the pH > 7, then it is basic
If pH is 1 then the solution is showing mostly acidic character,which is least basic in its character.
So if the pH is 1, which is most acidic and least basic solution that is lowest OH⁻ ion concentration.
The answer is (1) CaCO3. The bond between C and O is covalent bond. And the bond between Ca2+ and CO3 2- ion is the ionic bond. So the compound CaCO3 satisfy this condition.
Answer: option 4. polar, with the chlorine end having a partial negative charge.
Explanation:
1) A polar bond is a covalent bond in which the electrons are pulled more strongly by one of the atoms and then they are not evely distributed between the two linked atoms.
2) That happens when the two atoms have diferent electronegativities.
3) As the per periodic table trend of the electronegativity, you can predict that the electronetativity of Cl is higher than that of P.
In fact, in a table of electronegativities you can find that the electronegativity of Cl is 3.16 while the electronegativity of P is 2.19.
This is a 3.16 - 2.19 = 0.97 difference.
As explained, that difference means that Cl will pull the electrons more strongly resulting if a partial negative charge on Cl and a partial positive charge on P, i.e. a polar bond.
