Help as soon as possible please tell why you chose A B C OR D

Ais a mountain created from eruptions of lava, ash, rocks, and hot gases.

Which element has the lowest electronegativity? calcium(ca) gallium(ga) selenium(se) bromine(br)

Which of the following is an indication that a substance has undergone a chemical change? a. no new product has been formed. b. the color of the substance has not changed. c. the original constitute has not changed. d. the molecular structure has changed.