What is the legal ruling on the following transgressions: praying without ablution or in a state of ritual impurity (janabah), speaking and eating during prayer, excessive talking after the opening takbeer, speaking and raising one's voice during the call to prayer (adhan), taking a false oath (al-yameen al-ghamus), evading prayer, not completing prayer, not mastering Al-Fatihah and Al-Tashahhud, audacity towards teachers, using obscene language, and disrespecting the Book of Allah?

The teacher is entrusted with a responsibility and is accountable for their students, and they must advise and guide them towards what is best for them. As for the issues mentioned:

1. Praying without Wudu' or while in a state of Janabah: Prayer is not accepted without purification, which is one of the conditions for the validity of prayer. Whoever does this intentionally, knowing its prohibition, has committed a grave sin, and some scholars have even deemed it an act of disbelief. 2. Talking during prayer: It is forbidden and invalidates the prayer if done intentionally, knowing its prohibition, because prayer is a communion with Allah that requires complete absorption. 3. Eating or chewing gum during prayer: It invalidates both obligatory and supererogatory prayers. If done with the intent of mockery, it is disbelief. 4. Excessive talking by those who have not yet entered prayer after the Takbirat al-Ihram: This is inappropriate and indicates a lack of mindfulness of standing before Allah. It also causes distraction for those who are praying. 5. Talking and raising one's voice during the Adhan: The Sunnah is to listen to the Adhan, repeat after the Mu'adhdhin, and supplicate afterwards. Indeed, some scholars have gone so far as to say it is obligatory to respond to the Mu'adhdhin. 6. Swearing a false oath (Yamin Ghamus) and excessive swearing: Excessive swearing is blameworthy, and the Yamin Ghamus is one of the gravest sins that plunges its perpetrator into the Hellfire. It does not require expiation but rather repentance and seeking forgiveness. 7. Some students avoiding prayer inside classrooms: Deliberately abandoning prayer is an act of disbelief in Allah Almighty; it is the distinction between a Muslim and a disbeliever. Lagging behind in congregational prayer is a sign of hypocrisy. 8. Some students arriving late for prayer and not completing the remaining Rak'ahs after the Imam's Taslim: This is evidence of belittling the importance of prayer, and whoever does so, disrespecting its sanctity, may be a disbeliever. 9. Some students not mastering Al-Fatihah and Al-Tashahhud: This is a shortcoming on everyone's part. Al-Fatihah is a pillar of prayer without which prayer is not valid, and it is obligatory for the ignorant to learn it. 10. Daring to use abusive language towards teachers: This contradicts the ethics of a Muslim. A teacher is like a parent, and it is a Muslim's duty to guard their tongue from anything that displeases Allah. 11. Habitual use of offensive and foul language: A Muslim is accountable for every word they utter, so they should speak good or remain silent. 12. Disrespecting the Book of Allah and touching it without Wudu': It is obligatory to protect and respect the Mus'haf, and the majority of scholars prohibit touching it without purification.

Finally, students are advised to fear Allah in private and in public, and to strive for good morals.