CBSE Class 8 Answered

Reaction with Water: 

           Metal   + Water → Metal hydroxide + Hydrogen

 Example:

           2Na + 2H₂O → 2NaOH + H₂↑

 Sodium reacts violently with cold water to form sodium hydroxide solution along with the evolution of hydrogen gas.

Reaction with Acids:

 Metal   +    Acid   →  Salt    +  Hydrogen

For example: Magnesium reacts with dilute hydrochloric acid to form magnesium chloride and hydrogen gas.

     Mg + HCl → MgCl₂ + + H₂↑

Al, Fe and Zn also react with dilute HCl to form corresponding metal chlorides and hydrogen gas.

The less reactive metals such as copper, silver and gold do not react with dilute acids.

2. Non-metals do not react with dilute acids to form salts and hydrogen gas.

Reaction with Oxygen:

Metal    +   Oxygen    →   Metal oxide (Basic oxide)

The metal oxides are basic in nature. The basic metal oxides turn red litmus to blue.

 Iron metal combines slowly with the oxygen of the air in the presence of water to form iron oxide. This iron oxide is the rust.

 2. Non-Metals react with oxygen to form non-metallic oxides.

Non-Metal    +   Oxygen  →   Non-Metal oxide(Acidic oxide) 

The non-metal oxides are acidic in nature. The acidic non-metal oxides turn blue litmus to red.

Mg    +      O2   →  MgO(Basic oxide)

MgO +   H2O     →       Mg(OH)2(Base)