Electronic transitions (i. e., absorption of uv or visible light) of the conjugated molecule butadiene can be approximated using the particle-on-a-line model, assuming one of the pi electrons can move along the whole four-carbon chain. a molecule of butadiene is found to absorb light of 215 nm corresponding to the electron being excited from the n=2 to n=3 levels. use this to determine the length, in angstroms, of the four-carbon chain to which the electron is confined.

Amachinist needs to remove a tight fitting pin of material a from a hole in a block made of material b. the machinist heats both the pin and the block to the same high temperature and removes the pin easily. what statement relates the coefficient of thermal expansion of material a to that of material b? a) the situation is not possible, heating block b will shrink the hole in the material as the material expands with increasing temperatureb) material b has the same coefficient of expansion as does material ac) material b has a negative coefficient of expansion and a has a positive coefficient of expansiond) material a has a greater coefficient of expansion than does material be) material b has a greate

When a light bulb shines, it gives off light energy and energy. a. heat b. potential c. chemical d. electrical

Suppose you increase your walking speed from 7 m/s to 13 m/s in a period of 2 s. what is your acceleration?