Question

Q3. What do you mean by amphoteric oxides? Give example and also give reactions
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Q4. What are alkalis? How they are formed, give any two reactions ?
Q5. Name any two metal which react vigorously with oxygen. How do we store them to avoid any hazard?
Q6. Why calcium and magnesium floats on the surface when reacts with water? Give reaction.
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Answer 1

Explanation:

3)An amphoteric oxide is one that can act as a base or as an acid. The non-metallic oxides are generally acidic and the metallic oxides are basic. ... Amphoteric oxides react with both acids and alkalis to form salt and water. Examples of amphoteric oxides are zinc oxide and aluminum oxide.

4)Alkali salts

Sodium hydroxide (NaOH) – often called "caustic soda" Potassium hydroxide (KOH) – commonly called "caustic potash" Lye – generic term for either of two previous salts or their mixture. Calcium hydroxide (Ca(OH)2) – saturated solution known as "limewater"

When any substance burns in oxygen it is called a combustion reaction. Potassium (lilac) burns most vigorously followed by sodium (orange-yellow) and then lithium (red), as you might expect.

Answer 2

Answer:

here's your answer dear...........

Explanation:

1.An amphoteric oxide is one that can act as a base or as an acid. The non-metallic oxides are generally acidic and the metallic oxides are basic. ... Amphoteric oxides react with both acids and alkalis to form salt and water. Examples of amphoteric oxides are zinc oxide and aluminum oxide.....

2.Alkali salts are soluble hydroxides of alkali metals and alkaline earth metals, of which common examples are: Sodium hydroxide (NaOH) – often called "caustic soda" Potassium hydroxide (KOH) – commonly called "caustic potash" ... Calcium hydroxide (Ca(OH)2) – saturated solution known as "limewater".....

3.sorry I don't know the third one..

4.Calcium starts floating because the bubbles of hydrogen gas formed stick to the surface of the metal. Magnesium does not react with cold water....

hope this will helpful to you.....

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