In a closed system for the reaction: A (g) + 2B (g) → AB₂ (g) The rate of the reaction increases when there is A) an increase in pressure
B) an increase in the reaction vessel
C) a decrease in the concentration of A
D) an increase in surface area of A

With the largest atoms and the smallest number of valence electrons and with the smallest atoms and the greatest number of valence electrons are the most reactive. a. nonmetals; metals b. nonmetals; transition elements c. transition elements; metals d. metals; nonmetals