Answer:
I believe Na
Explanation:
Copper, because it is the only metal out of all of them.
Therefore copper is the only element that can loose electrons to have a positive charge, it is the most likely to become a cation.
Answer:
The Net reaction is
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-

-
Explanation:
From the Question we are told that the buffers are
and 
When NaOH is added the Net ionic reaction would be
-

-

-
Answer:
STP stands for Standard Temperature and Pressure. NTP stands for Normal Temperature and Pressure.
Explanation:
STP is set by the IUPAC as 0°C and 100 kPa or 1 bar.
NTP is set at 101.325 kPa but uses 20°C as the temperature