What are the seven surahs of the Qur’an that provide salvation, and what is the reward for reciting each of them, knowing that among these surahs are: Ad-Dukhan, Al-Mulk, Ar-Rahman, Al-Waqi'ah, and Ya-Sin? And is this information correct?

No authentic evidence has been found to substantiate what the questioner mentioned regarding surahs that protect one from the torment of the grave. There is a weak hadith narrated from Ibn Abbas stating that Surat Al-Mulk protects from the torment of the grave, and another weak hadith from Khalid bin Ma'dan, who said that Surat As-Sajdah protects from the torment of the grave. It is authentically reported from Jabir bin Abdullah that the Prophet, peace and blessings be upon him, would not sleep until he had recited Surah As-Sajdah and Surah Al-Mulk.

The entire Quran is a means of salvation for its reciter and one who acts upon its teachings. There are hadiths and narrations regarding the virtues of specific surahs:

Yasin: There is a good hadith from Abu Hurayrah stating, "Whoever recites Yasin during the night will wake up forgiven." It is recited for a dying person to bring down mercy and facilitate the departure of the soul. Most of the hadiths regarding its virtues are weak, such as the hadith, "Everything has a heart, and the heart of the Quran is Yasin." Al-Mulk: There is a hasan (good) hadith from Abu Hurayrah stating, "Indeed, there is a surah in the Quran of thirty verses that interceded for a man until he was forgiven, and it is Surah Tabarak Alladhi biyadihil-Mulk (Al-Mulk)." Al-Waqi'ah: There is a weak hadith from Ibn Mas'ud stating, "Whoever recites Surah Al-Waqi'ah every night will never be afflicted by poverty." Ar-Rahman: Weak hadiths have been reported regarding its virtues, including, "Everything has a bride, and the bride of the Quran is Ar-Rahman," and "The reciter of Al-Hadid, and Idhā Waq‘ati Al-Waqi‘ah, and Ar-Rahman is called in the dominion of the heavens and the earth 'Dweller of Firdaws'."