C magnetic repulsion, forgive me if I’m wrong
When E° cell is an electrochemical cell which comprises of two half cells.
So,
when we have the balanced equation of this half cell :
Al3+(aq) + 3e- → Al(s) and E°1 = -1.66 V
and we have also this balanced equation of this half cell :
Ag+(aq) + e- → Ag(s) and E°2 = 0.8 V
so, we can get E° in Al(s) + 3Ag (aq) → Al3+(aq) + 3Ag(s)
when E° = E°2 - E°1
∴E° =0.8 - (-1.66)
= 2.46 V
∴ the correct answer is 2.46 V
Cs -137 has a half life of about 30 years. If 60 years pass, there is two half lives passed so 1/2 * 1/2= 1/4. Take 1/4 and multiply it with the mass given:
(1/4)*20mg=5mg left
<u>Answer:</u> The product side must be 
<u>Explanation:</u>
Single displacement reaction is defined as the reaction in which more reactive metal displaces a less reactive metal from its chemical reaction.

Metal C is more reactive than metal A.
The reactivity of metal is determined by a series known as reactivity series. The metals lying above in the series are more reactive than the metals which lie below in the series.
Law of conservation of mass states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form. This also means that total number of individual atoms on reactant side must be equal to the total number of individual atoms on the product side.
When zinc metal reacts with hydrochloric acid, it leads to the production of zinc chloride and hydrogen gas. The chemical reaction follows:

<u>On reactant side:</u>
Number of zinc atoms = 1
Number of hydrogen atoms = 2
Number of chlorine atoms = 2
<u>On product side:</u>
Number of zinc atoms = 1
Number of hydrogen atoms = 2
Number of chlorine atoms = 2
Hence, the product side must be 
D = m / V
D = 2790 g / 205 mL
D = 13.60 g/mL