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1)The difference between physical and chemical change are:-
Physical change:- •It is reversible
•Example:- melting of ice, folding paper,etc.Here when ice melt we can again freeze it, when we fold the paper we can again unfold it.
Chemical change:-• It is not reversible
• Example:- cutting of trees, cutting of papers etc When we cut tree we cannot fix it again
2) Four characteristics of chemical change are:-
- Colour change
- Odor is produced
- Temperature is changed
- It is not reversible
3)Galvanization:-Galvanisation or galvanization (or galvanizing as it is most commonly called) is the process of applying a protective zinc coating to iron or steel, to prevent rusting. The most common method is hot dip galvanizing, in which steel sections are submerged in a bath of molten zinc.
Crystallization:-Crystallization is a process whereby solid crystals are formed from another phase, typically a liquid solution or melt. Crystal. Crystal is a solid particle in which the constituent molecules, atoms, or ions are arranged in some fixed and rigid, repeating three-dimensional pattern or lattice.
4) Rust is a reddish- or yellowish-brown flaking coating of iron oxide that is formed on iron or steel by oxidation, especially in the presence of moisture.
Rust will only occur when the metal will be in the contact of water and air. If any one of them will be not there then rust will not be produced.
We can prevent rusting by following ways:-
- Paint it - Paint the metal with any durable acrylic paint.
- By Galvanization procesd also we can prevent the rusting of iron.
5)By adding other elements, such as nickel, molybdenum, titanium, niobium, manganese, etc steel is make stainless steel
6) When vinegar and baking soda are first mixed together, hydrogen ions in the vinegar react with the sodium and bicarbonate ions in the baking soda. The result of this initial reaction is two new chemicals: carbonic acid and sodium acetate. The second reaction is a decomposition reaction.