Answer:
When 0.250 moles of a gas is placed in a container at 25 °C, it exerts a pressure of 700 mm Hg.
Explanation:
Answer:
D. Ni²⁺
Explanation:
We know at once that the answer cannot be A or C, because Ni and Cu are already in their lowest oxidation states.
The correct answer must be either B or D.
An electrolytic cell is the opposite of a galvanic cell. In the former, the reaction proceeds spontaneously. In the latter, you must force the reaction to occur.
One strategy to solve this problem is:
- Look up the standard reduction potentials for the half reaction·
- Figure out the spontaneous direction.
- Write the equation in the reverse direction.
1. Standard reduction potentials
E°/V
Cu²⁺ + 2e⁻ ⟶ Cu; 0.3419
Ni²⁺ + 2e⁻ ⟶ Ni; -0.257
2. Galvanic Cell
We reverse the direction of the more negative half cell and add.
<u>E°/V
</u>
Ni ⟶ Ni²⁺ + 2e⁻; 0.257
<u>Cu²⁺ + 2e⁻ ⟶ Cu; </u> 0.3419
Ni + Cu²⁺ ⟶ Cu + Ni²⁺; 0.599
This is the spontaneous direction.
Cu²⁺ is reduced to Cu.
3. Electrochemical cell
<u>E°/V</u>
Ni²⁺ + 2e⁻ ⟶ Ni; -0.257
<u>Cu ⟶ Cu²⁺ + 2e⁻; </u> <u>-0.3419</u>
Cu + Ni²⁺ ⟶ Ni + Cu²⁺; -0.599
This is the non-spontaneous direction.
Ni²⁺ is reduced to Ni in the electrolytic cell.
Answer:
D. 2:5
Explanation:
It has 5 valency electrons
Answer:
The plum pudding model of the atom agreed with the nuclear model
Explanation:
Answer:
c) 30
Explanation:
In an atom , the relation between the subatomic particles of the atom are given as follows -
For a neutral atom ,
Atomic number = number of protons = number of electrons ,
Mass number = number of protons + number of neutrons,
Hence , from the given information of the question,
Atomic number of Manganese = 25 ,
mass number of Manganese = 55 ,
Now, to calculate the number of neutrons , the above relation can be used -
Mass number = number of protons + number of neutrons,
Rearranging ,
number of neutrons = Mass number - number of protons
substituting the respective values ,
number of neutrons = 55 - 25 = 30 .
