Question

what are the main reasons for launching civil disobedience movement

Answer 1

to break the salt law
to remove the rowlatt act
I think this is all

Answer 2

(i) Failure of the Simon Commission : The Simon Commission was constituted in response to the nationalist movement. But the Commission failed to satisfy the Indian people and the leaders. All the parties, including the Congress and the Muslim League, participated in the demonstrations. In an effort to win them over the Viceroy, Lord Irwin, announced in October 1929, a vague offer of dominion status. But even this failed to satisfy the leaders.
(ii) Puma Swaraj : In December 1929, under the presidency of Jawaharlal Nehru, the Lahore Congress formalised the demand of ‘Puma Swaraj’ or full independence for India. It was declared that 26th January, 1930, would be celebrated as the Independence Day when people were to take a pledge to struggle for complete independence. But the celebrations attracted very little attention. So Mahatma Gandhi had to find a way to relate this abstract idea of freedom to more concrete issues of everyday life.
(iii) Rejection of Gandhi’s Eleven Demands : On 31st January, 1930, Mahatma Gandhi, in a statement, put forward Eleven Demands to correct the wrongs done to the Indians.