Yep the national language of Israel is Modern Hebrew. The rejection of Yiddish as an alternative reflected the conflict between religious and secular forces. Many in the larger, secular group wanted a new national language to foster a cohesive identity, while traditionally religious Jews desired that Hebrew be respected as a holy language reserved for prayer and religious study. This conflict also reflected the opposing views among secular Jews worldwide, one side seeing Hebrew (and Zionism) and the other Yiddish (and Internationalism) as the means of defining emerging Jewish nationalism
Also a lot of jewish refugees found Yiddish to be a foreign language to them and communication in Hebrew made it more practical.
