First find the oxidation states of the various atoms:
<span>in Cr2O2 2- Cr @ +1; In NH3 N @ +3; in CrO3 Cr @ +3, N2 N @ 0 </span>
<span>Note that N gained electrons, ie, was reduced; Cr was oxidized </span>
<span>Now there is a problem, because B has NH4+ which the problem did not, and is not balanced, showing e- in/out </span>
<span>B.NH4+ → N2 </span>
<span>Which of the following is an oxidation half-reaction? </span>
<span>A.Sn 2+ →Sn 4+ + 2e- </span>
<span>Sn lost electrons so it got oxidized</span>
Answer:
The Third Law of thermodynamics states that the entropy of a pure substance in a perfect crystalline state at zero temperature is zero.
Answer: 2.88×
atoms 
Explanation: First, using stoichiometry, we must convert this from grams to moles, then from moles to atoms.
1. For the first step, we should also look at the periodic table to find the molar mass of the compound, then use that as the denominator.
2. Now that it is converted to moles, we must convert it to atoms by multiplying it by Avogadro's number.
With this information, we know that there are 
total atoms in 0.680 grams 
.
I hope this helps! Pls give brainliest!! :)
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit The word was coined by William Wheel at the request of the scientist Michael Faraday from the Greek words electron, meaning amber and hods, a way.
