Context: In February 1939, he received news from his sisters that his mother was dying. On 10 February 1939, Pope Pius XI died. Roncalli was unable to see his mother for the end as the death of a pontiff meant that he would have to stay at his post until the election of a new pontiff. Unfortunately, she died on 20 February 1939, during the nine days of mourning for the late Pius XI. He was sent a letter by Cardinal Eugenio Pacelli, and Roncalli later recalled that it was probably the last letter Pacelli sent until his election as Pope Pius XII on 2 March 1939. Roncalli expressed happiness that Pacelli was elected, and, on radio, listened to the coronation of the new pontiff. 

Question: When did he hear that his mother was dying?
Answer: February 1939

Question: When did Pope Pius XI die?
Answer: 10 February 1939

Question: When did his mother die?
Answer: 20 February 1939

Question: Who sent him the letter informing him of his mother's death?
Answer: Cardinal Eugenio Pacelli

Question: When was Pope Pius XII elected?
Answer: 2 March 1939

Question: What did Cardinal Eugenio Pacelli receive in February 1939?
Answer: Unanswerable

Question: When did Cardinal Eugenio Pacelli die?
Answer: Unanswerable

Question: During what time did Cardinal Eugenio Pacelli die?
Answer: Unanswerable

Question: When was Roncalli elected as Pope?
Answer: Unanswerable

Question: How did Pope Pius XI keep track of the election of the new Pope?
Answer: Unanswerable