I would say D and if that's not it it's A
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Certain fish species use bioluminescence as a form of "night light". Some use it for communication. Certain species of crustaceans send out coded signals to others of their own kind during mating season. Other creatures use bioluminescence as a trap.
Answer:
1) high pH is required
2) other ions are precipitated along with the strontium ions
Explanation:
According to the solubility rules all phosphates are insoluble except those of sodium, potassium, and ammonium. This implies that strontium phosphate is insoluble in water. This explains why strontium ions can be precipitated from drinking water supply using phosphate. The main problem with the precipitation of strontium using phosphate is that it usually requires a high pH as the precipitation occurs under very alkaline conditions.
The main reason why the results may not be accurate is that other ions are precipitated along with the strontium such as calcium ions and magnesium ions. This may lead to inaccurate determination of the amount of strontium ions present.
The number of electrons shared between the atoms in a I₂ molecule is two (2).
Explanation:
An iodine atom has 53 electrons and its electron configuration is;
2. 8. 8. 18. 17
1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²4d¹⁰5p⁵
Note that the outermost p shell has 5 electrons while it can accommodate a maximum of 6 for stable electron configuration. Therefore an Iodine atom needs one (1) electron to acquire nobility. Two Iodine atoms will, therefore, share two electrons (each from one of their p sub-shell ) by covalent bonds to form I₂
Learn More:
For more on electron configuration and nobility check out;
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