Question

P(-2,3), Q(1,2), R(4, 1)​

Answer 1

Step-by-step explanation:

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Answer 2

Answer:

When magnesium ribbon is exposed to air, it forms a layer of magnesium oxide on its surface. This layer of magnesium oxide, being a stable compound, prevents further reaction of magnesium with oxygen. Hence, it should be cleaned before burning in air to remove this layer so that the metal can be exposed to air properly.