Why should a magnesium ribbon be cleaned before burning in air ?

NCERT Solution for Class 10 Science Chapter 1 

Q. Why should a magnesium ribbon be cleaned before burning in air ?

Answer:
Magnesium gets covered with a layer of magnesium oxide when kept in air for a long time. This layer hinders the burning of magnesium. Hence, it is to be cleaned before burning.

similar content:-

write a balanced chemical equation with state symbol for the following reactions.(I) solutions of sulphate and the solution of sodium chloride. (ii)sodium hydroxide solution react with hydrochloric acid solution to produce sodium chloride solution and water.

a solution of a substance X is used for whitewashing. (i) name the substance X and write its formula. (ii) write the reaction of the substance X named in (i) above with water

 

why is the amount of gas collected in one of the test tube in activity 1.7 double of the amount collected in the other? Name this gas.