Question

What is thermit reaction?writes it's balanced equations.how is it used to join railway tracks or cracked machine parts?

Answer 1

Here is your  answer-

The thermit reaction is the reaction of metal oxide with aluminium.The aluminium acts as a reducing element and the reaction is highly exothermic and hence called a thermite reaction.The aluminium reduces the oxide of another metal.Most of the it is Iron Oxide.The reaction can be shown as-

Fe2o3+Al=Fe+Al2O3

Hope it helps.

Answer 2

it is thermite reaction

2Al + Fe2O3 ----> Al2O3 + 2Fe + Heat