Answer:
1. Chromium
2. Chlorine.
3. Chlorine.
4. Chromium.
5. 12 electrons.
Explanation:
Hello,
In this case, the given reaction with the appropriate oxidation states turns out:

In such a way, the oxidation half-reaction is written for chromium as the reducing agent so it is oxidized from +3 to +6, nonetheless, since there are two chromiums undergoing such change, 6 electrons are being transferred as shown below:

On the other hand, chlorine's reduction half-reaction as the oxidizing agent result from the transfer of 6 electrons as well from +1 to 0, nonetheless, there are 6 chlorines undergoing such change:

Therefore, there are 12 electrons that are being transferred, 6 for chromium and 6 for chlorine.
Best regards.
1L = 1000ml
1ml = 1cm^3
2.1L = 2100mL = 2100cm^3
Cu = 63.546
N= 14.001 g/mol
O= 15.999 g/mol * 3 = 47.997
Copper (II) Nitrate has a MW of 125.544 g/mol
6.25 x 125.544
= 784.65 <--- is your answer, if there were was a multiple choice or not :)
The question is incomplete, the complete question is;
The table above summarizes data given to a student to evaluate the type of change that took place when substance X was mixed with water. The student claimed that the data did not provide enough evidence to determine whether a chemical or physical change took place and that additional tests were needed. Which of the following identifies the best way to gather evidence to support the type of change that occurred when water and Xwere mixed?
A. Measuring the melting point of the mixture of water and X
B. Adding another substance to the mixture of water and X to see whether a solid forms
C Measuring and comparing the masses of the water, X, and the mixture of water and X
D Measuring the electrical conductivities of X and the mixture of water and X
Answer:
D Measuring the electrical conductivities of X and the mixture of water and X
Explanation:
Unfortunately, I am unable to reproduce the table here. However, from the table, the temperature of the of the mixture of the solid X and water was 101.6°C. This is above the boiling point of water and way below the temperature of the solid X.
This goes a long way to suggest that there was some kind of interaction between the water and X which accounted for the observed temperature of the system of X in water.
The only way we can be able to confirm if X actually dissolved in water is to measure the conductivity of the water. dissolved solids increase the conductivity of water.
Answer:
0.0011 mol/L.s
Explanation:
The average rate of disappearing of the reagent is the variation of the concentration of it divided by the time that this variation is being measured. The reaction rate, is proportional to the coefficient of the substance, so, for a generic reaction:
aA + bB --> cC + dD
rate = -(1/a)Δ[A]/Δt = -(1/b)Δ[B]/Δt = (1/c)Δ[C]/Δdt = (1/d)Δ[D]/dt
The minus sign is because of the reagent is desapering, so:
rate = -(1/2)*(0.0209 - 0.0300)/(10 - 6)
rate = 0.0011 mol/L.s