In which shell are the valence electrons of the elements in period 2 found?
(1) 1 (3) 3
(2) 2 (4) 4

Choose an equation that represents an enzyme-catalyzed reaction. (a) enzyme + substrate → enzyme-substrate complex (b) enzyme + substrate ←−→ enzyme + products (c) enzyme + substrate ←−→ enzyme-substrate complex → enzyme + products (d) enzyme + substrate ←−→ enzyme-substrate complex → enzyme-substrate complex + products

Describe at least two advantages and two disadvantages of using hydropower as a source of energy.

Mercury turns to a vapor at 629.88 k. how much heat is lost when 75.0 g of mercury vapor at 650 k condenses to a liquid at 297 k?