وَإِذَا ٱلْأَرْضُ مُدَّتْ
Sentence structure
Coordinated وَإِذَا introduces another temporal condition. مُدَّتْ is a passive perfect and ٱلْأَرْضُ its nominative deputy subject.
Ayah summary
For the gathering, the earth will be stretched out and levelled.
وَإِذَا — And when
Grammar: وَ coordinates and إِذَا is a non-jussive conditional time adverb.
ٱلْأَرْضُ — the earth
Grammar: ٱل is the definite article and أَرْضُ the nominative deputy subject of passive مُدَّتْ.
مُدَّتْ — is spread
Grammar: A passive third-person feminine-singular perfect; final تْ is the feminine marker.