Question

I. Clean a magnesium ribbon about 2 cm long by rubbing it with sandpaper. Hold it with a

pair of tongs. Burn it using a spirit lamp or burner and collect the ash so formed in a

watch-glass.

1. Magnesium ribbon is rubbed before burning because it has a coating of

A. basic magnesium carbonate

B. basic magnesium oxide

C. basic magnesium sulphide

D. basic magnesium chloride

2. What is the colour of magnesium ribbon?

A. White

B. Black

C. Grey

D. Yellow

3. What is the chemical name of the powder obtained in the activity?

A. magnesium carbonate

B. magnesium oxide

C. magnesium sulphide

D. magnesium chloride

4. Which compound is formed when the powder obtained reacts with water?

A. Magnesium sulphate

B. Magnesium oxide

C. Magnesium carbonate

D. Magnesium hydroxide​

Answer 1

Answer:

(1)basic magnesium oxide

Step-by-step explanation:

(2) white

(3) magnesium oxide

(4) magnesium hydroxide

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Answer 2

The questions are answered below:

1. Magnesium ribbon is rubbed before burning because it has a coating of- B. basic magnesium oxide.

• Magnesium is a very reactive alkaline metal that reacts with the oxygen present in the air and forms a coating of basic magnesium oxide.
• Hence, to burn pure magnesium while performing an activity, the magnesium ribbon is rubbed with sandpaper.

2. The color of the magnesium ribbon is- A. White.

• Magnesium ribbon is silvery white with no odour.

3. The chemical name of the powder obtained in the activity is- B. magnesium oxide.

• The magnesium undergoes a combustion reaction and forms basic magnesium oxide. The reaction is exothermic as energy is released while burning magnesium ribbon.

4. When the powder obtained reacts with water, the compound formed is- D. Magnesium hydroxide.

• The magnesium hydroxide formed due to a chemical reaction between magnesium oxide and water is basic in nature.