What does "A" represent in a the standard form of a double replacement reaction? a.) otion b.) cation

Asap! how do you lengthen a pattern piece? (family and consumer science, sewing)

The human eye contains a molecule called 11-cis-retinal that changes shape when struck with light of sufficient energy. the change in shape triggers a series of events that results in an electrical signal being sent to the brain that results in vision. the minimum energy required to change the conformation of 11-cis-retinal within the eye is about 164 kj/mol.

What is the vapor pressure of a solution with a benzene to octane?