Answer:
The temperature is 69.05 K.
Explanation:
We have,
Number of moles are 6
Pressure is 3.4 atm and a volume of 10 liters.
It is required to find the temperature. It can be calculated using gas law equation. It says that,

P is pressure
V is volume
n is number of moles
R is gas constant, 
T is temperature
Plugging all the values we get :

So, the temperature is 69.05 K.
Answer:
B. Cu + 4HNO3 → Cu(NO3)2 + 2H2O + 2NO2
Explanation:
Hello,
In this case, we should understand oxidizing agents as those substances able to increase the oxidation state of another substance, therefore, in B. reaction we notice that copper oxidation state at the beginning is zero (no bonds are formed) and once it reacts with nitric acid, its oxidation states raises to +2 in copper (II) nitrate, thus, in B. Cu + 4HNO3 → Cu(NO3)2 + 2H2O + 2NO2 nitritc acid is acting as the oxidizing agent.
Moreover, in the other reactions, copper (A.), sodium (C. and D.) remain with the same initial oxidation state, +2 and +1 respectively.
Regards.