In electrochemical cell notation, A double vertical line ( || ) represents a salt bridge or porous membrane separating the individual half-cells.

The correct answer is Option A.

The purpose of a salt bridge is not to move electrons from the electrolyte, rather maintain charge balance because the electrons are moving from one-half cell to the other. The electrons flow from the anode to the cathode thus if a salt bridge is removed between the half cells, the voltage becomes zero.
 

The correct answer is Option D
For the cell reaction
Zn(s) + 2Ag⁺ (aq) →2Ag(s) + Zn²⁺ (aq) 
The two half cell reactions are
Zn(s) →Zn²⁺ (aq) + 2e⁻
Ag+(aq) + e −→Ag(s) ×2
Zn(s) + 2Ag(aq) →Zn²⁺ + 2Ag(s)
Therefore Zn is oxidised and as such acts as -ve electrode or anode. Ag+Ag+ ions get reduced as such the Ag electrode acts as a cathode or _ve electrode. Therefore cell representation is
Zn ∣∣Zn2+∣∣∣Ag+∣∣Ag

The correct answer is option D.

Reduction potential refers to the voltage required to reduce a material under standard conditions. If a material has a higher reduction potential it takes more energy to reduce it than a lower reduction potential material. Therefore the higher reduction potential material is actually oxidized to reduce the lower reduction potential material.
Cathode- The electrode where reduction occurs and
The one with the highest reduction potential selected as the reduction half-reaction and therefore is cathode .

The correct answer is Option A
Zn + Cu⁺⁺ →Zn⁺⁺ + Cu
At cathode: Cu⁺⁺ + 2e⁻ →Cu
At anode: Zn −2e⁻ →Zn
∴Cell representation
Zn ∣Zn⁺⁺ ∣∣Cu⁺⁺ ∣Cu

Daniel cell is a galvanic cell. The reduction half-reaction occurs on the copper electrode while the oxidation half-reaction occurs on the zinc electrode. These two portions of the cell are also called half-cells or redox couples. The copper electrode may be called the reduction half-cell and the zinc electrode, the oxidation half-cell. In Daniel, cell Zinc acts as an anode and copper act as a cathode.

The reaction at the anode is oxidation and that at the cathode is reduction. Here, the anode is positive and cathode is the negative electrode. The reaction at the anode is oxidation and that at the cathode is reduction.

The correct answer is Option A.

For a good salt bridge, the velocities of ions should be the same. If the velocities are not the same, then the ions would not be able to neutralize the charge equally in both half cells. Consequently, an opposite force would be developed that restricts the flow of current. For KNO3, the velocities of K+and NO3- are nearly the same. Therefore, it is used to make salt bridges

The correct answer is Option D
oxidation
The reaction at the anode is oxidation and that at the cathode is reduction. The electrons are supplied by the species getting oxidized. They move from anode to the cathode in the external circuit.

The electrode having lower reduction potential will have lesser tendency to gain electrons.
i.e. act as anode.