Answer:
Human activities have a tremendous impact on the carbon cycle
Explanation:
Burning fossil fuels, changing land use, and using limestone to make concrete all transfer significant quantities of carbon into the atmosphere. ... The ocean absorbs much of the carbon dioxide that is released from burning fossil fuels.
Answer:
the chemical change occur in burning paper.
boiling water does not make any chemical change
melting gold "
dissolving sugar in water "
in these examples the reactant remains as the same , even if you melt gold it is gold itself, it only change its state.
C) is higher for nonpolar substances than for polar ones
Answer : The hydroxide ion concentration of a solution is, 
Explanation :
As we know that:
pH : It is defined as the negative logarithm of hydrogen ion concentration.
Mathematically,
![pH=-\log [H^+]](https://tex.z-dn.net/?f=pH%3D-%5Clog%20%5BH%5E%2B%5D)
Similarly,
pOH : It is defined as the negative logarithm of hydroxide ion concentration.
Mathematically,
![pOH=-\log [OH^-]](https://tex.z-dn.net/?f=pOH%3D-%5Clog%20%5BOH%5E-%5D)
Given:
pOH = 6.42
![6.42=-\log [OH^-]](https://tex.z-dn.net/?f=6.42%3D-%5Clog%20%5BOH%5E-%5D)
![[OH^-]=3.8\times 10^{-7}M](https://tex.z-dn.net/?f=%5BOH%5E-%5D%3D3.8%5Ctimes%2010%5E%7B-7%7DM)
Therefore, the hydroxide ion concentration of a solution is,
Answer is: a single atom of chlorine.
Chlorine has electron configuration: ₁₇Cl 1s²2s²2p⁶3s²3p⁵.
According to his electron configuration, chlorine needs one electron to achive noble gas configuration (most stable because <span>valence shell is filled).
NaCl, H</span>₂O and Ar have stable electron configuration.
