<span> the atmosphere holds about 21 per cent oxygen. Over the Earth’s 4.6 billion year history, oxygen did not appear in the atmosphere until perhaps about 2.5 billion years ago. Since then, oxygen levels have fluctuated in tandem with global geological and biological events, such as mass extinctions.</span>
Ba3PO4 is not neutral, it is positive. (NH4)2SO4 is neutral, the charges cancel.
Mg2OH is not neutral, it is positive. LiF2 is not neutral, it is negative. CaOH is not neutral, it is positive. The answer is (NH4)2SO4, correct ions will have a neutral charge.
Answer:
Option 4 ) 1-butyne
Explanation:
In organic chemistry, you should use IUPAC convention in order to name an organic compound. First of all, you should identify the lenght of the organic chain, for this case, you have 5 C atoms, but in fact, you have a triple bond (which would be a substitute: ethynil-) as a substitute, so the main skeleton would have 4 C atoms (a butane)
Then, you start by numbering carbon N° 1 as the one that has the substitute (triple bound)-starting from the right, it would be the second C):
CH₃-CH₂-CH₂-C≡CH
Which will finally leads us to 1-butyne
Atoms are smaller than molecules, and they are also the smallest building blocks of matter. Atoms make up molecules when two or more atoms bond.
The molar mass of copper is 63.55 g/mol. So, you convert grams to moles 127.08/63.55 =1.999 moles copper. Now, 1 mole = 6.022e23 atoms, so multiply # of moles by 6.022e23. 1.999 x 6.022e23= # of atoms of copper.
