Question

When magnesium ribbon is burnt it produces:
A) Magnesium hydroxide
B) Magnesium oxide
C) Magnesium chloride
D) Magnesium sulphate

Answer 1

Magnesium metals and its alloys are extremely explosive hazards. Upon burning in air, magnesium reacts with the oxygen present in the air and forms a white-coloured substance. Refer to the oxidation reaction of magnesium with oxygen upon heating.

Complete step by step solution:
Magnesium belongs to the group 2 of the periodic table, also called alkaline earth metals. Magnesium in molten form, powder form or in ribbon form catches fire easily. That's why magnesium metal in different forms or its alloys are highly inflammable and are thus explosive hazards. When magnesium is in its metal form, it burns very easily in air. Magnesium just needs a source of energy for burning. The flame of the burner provides a source of heat to the magnesium metal and thus it overcomes its activation energy. Activation energy is the minimum energy required in order for a chemical reaction to proceed. When the magnesium ribbon burns, it reacts with the oxygen present in air to form white - coloured powder called ‘magnesium oxide’, having chemical formula as $MgO$ . Oxygen and magnesium combine in a chemical reaction to form magnesium oxide. The chemical reaction is:
$Mg + {O_2}({\text{in air)}} \to MgO$
Since, in the chemical reaction there is addition of oxygen, the reaction is an oxidation reaction.

Hence, the answer is option B.

Note: Reaction of magnesium metal with oxygen is an exothermic reaction. An exothermic reaction is the one in which there is a release of energy. Magnesium gives two electrons to oxygen atoms to form magnesium oxide.