Answer:
In Tcl the words in a command are always exposed to two layers of interpretation: First, Tcl interprets them and prepares them as arguments to a routine. Second, the routine interprets those arguments according to its own principles. double substitution occurs when Tcl performs substitutions on original command and a routine then performs substitutions on the resulting arguments. Care is required in these cases to avoid errors, including vulnerability to injection attacks.
Explanation:
this probably wont help but here
An even distribution of electrons creates non-polar molecules with no regions of charge concentration, while an uneven distribution causes regions of polarity.
Any buffer exists in this equilibrium
HA <=>
In a buffer, there is a large reservoir of both the undissociated acid (HA) and its conjugate base (
)
When a strong acid is added, it reacts with the large reservoir of the conjugate base (
) forming a salt and water. Since this large reservoir of the conjugate base is used, the ph does not alter drastically, but instead resist the pH change.