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Answers
I will give you answer
Answer:-
- Across
1) This change are usually temporary.
➝ Physical
2) The brown layer is formed on the surface of iron objects.
➝ Rust
3) A chemical change is a ___ reactions.
➝ Chemical
- Down
1) The brown colour substance on iron objects is soft and ___ .
➝ Porous
2) These are substances with definite geometrical shape.
➝ Crystal
3) The process of coating a layer on zinc of iron objects.
➝ Galvanization
↪ More info about it ↩
Galvanization
➝ It is a process that involves coating iron with and thin layer of zinc. As zinc, more reactive than iron it reacts with oxygen in presence of atmosphere and thus prevents iron from rusting. Iron coated with zinc is called galvanized iron.
Galvanized steel is not used for food containers since acids in food containers zinc forming poisonous compounds.
Rusting
➝ When a piece of iron is left out in moist air it slowly changes to a dull brittle brown substance called rust formation of rust on the surface of iron is called rusting of iron.
Rusting can be prevented by
- Using oil or grease
- Applying oil paint
- Applying coal tar
- Using enamel coating
- Alloying
- Tin plating
Physical change
➝ A physical change is a temporary change. In this change no new substances are formed or produced and the change is reversible. There is no change in energy.
Examples:-
- breaking of a glass tumbler
- drying of clothes
- sublimation , many more.
Chemical change
➝ A chemical change is a permanent change in which the original substance losses its own composition and properties. This change is permanent and irreversible. In this, change Energy is it evolved or absorbed.
Examples:-
- rusting of iron
- digestion of food
- respiration, many more.
