Answer:
Give an example of each of the following chemical changes.
(a) A photochemical reaction involving
(i) silver salt
(ii) water
(b) A reaction involving
(i) blue solution
(ii) formation of dirty green precipitate
(c) Two gases combine to form white solid.
(d) A reaction where colour change is noticed.
Explanation:
a) A photochemical reaction involving silver salt is used in black and white photography.
AgCl breaks down and converts into Ag during this photochemical reaction.
(ii) Photochemicalreaction involving water takes place in plants during the photosynthesis process.
Plants prepare food(carbohydrate) by using sunlight water and CO2 gas.
(b) A reaction involving
(i) blue solution:
For example reaction of copper sulfate solution with an iron nail.
When an iron nail is placed in CuSO4 blue color solution, then it changes to green color and reddish-brown solid deposits at the bottom of the container.
(ii) Reaction of ferrous sulfate with NaOH forms a dirty green precipitate of ferrous hydroxide.
(C) Two gases combine and form a white solid:
For example when HCl gas reacts with ammonia gas, then a white solid of ammonium chloride will be formed.
(d) A reaction where the color change is noticed.:
When an iron nail is placed in CuSO4 blue color solution, then it changes to green color and reddish-brown solid deposits at the bottom of the container.
