A Life for the Tsar is a  Russian libretto with four acts, Tosca an Italian libretto has how many acts?
Tosca Tosca (] ) is an opera in three acts by Giacomo Puccini to an Italian libretto by Luigi Illica and Giuseppe Giacosa. It premiered at the Teatro Costanzi in Rome on 14 January 1900. The work, based on Victorien Sardou's 1887 French-language dramatic play, "La Tosca", is a melodramatic piece set in Rome in June 1800, with the Kingdom of Naples's control of Rome threatened by Napoleon's invasion of Italy. It contains depictions of torture, murder and suicide, as well as some of Puccini's best-known lyrical arias.
The Tale of Tsar Saltan (Rimsky-Korsakov) The Tale of Tsar Saltan (Russian: Сказка о царе Салтане , "Skazka o Tsare Saltane") is an opera in four acts with a prologue (a total of seven scenes) by Nikolai Rimsky-Korsakov. The libretto was written by Vladimir Belsky, and is based on the poem of the same name by Aleksandr Pushkin. The opera was composed in 1899–1900 to coincide with Pushkin's centenary, and was first performed in 1900 in Moscow, Russia.