Answer: I2 is the Oxidant; while the 2S2O3(-2) is the reductant.
Explanation:
An Oxidant is any substance that oxidizes, or receives electrons from, another; in so doing, it becomes reduced in oxidation number.
A Reductant thus exactly the opposite.
Note that the equation provided shows that Iodine (I2) received an electron to become NEGATIVELY CHARGED:
I2 --> 2I-.
The oxidation number reduced from 0 to -1.
In contrast, the oxidation number of 2S2O3(-2) increases from -4 to -2.
Thus, I2 is the Oxidant; while the 2S2O3(-2) is the reductant.
Answer: a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation.
Explanation: definition
and 
.
Assuming complete decomposition of both samples,
First compound:
; 
of the first compound would contain
Oxygen and mercury atoms seemingly exist in the first compound at a 
ratio; thus the empirical formula for this compound would be where the subscript "1" is omitted.
Similarly, for the second compound
; 
of the first compound would contain
and therefore the empirical formula
.
D. Changes
Hope this helps :)
