An electrochemical voltaic cell setup consists of two half cells, an anode, a cathode, an external circuit, and a salt bridge. When a reaction occurs, ion migration takes place through the 1. anode
2. cathode
3. salt bridge
4. external circuit

answer: a chemical reaction

explanation:

im not wrong

a  solution  is always transparent, light passes through with no scattering from solute particles which are molecule in size. the  solution  is homogeneous and does not settle out. a colloid is intermediate between asolution  and a  suspension. while asuspension  will separate out a colloid will not.

acid rain does not usually kill trees directly. instead, it is more likely to weaken the trees by damaging their leaves, limiting the nutrients available to them, or poisoning them with toxic substances slowly released from the soil. the main atmospheric pollutants that affect trees are nitrates and sulphates.

a is the correct answer