which one of the following is a physical change?
a. in cold weather, water condenses on the inside surface of single pane windows.
b. grape juice left in an open unrefrigerated container turns sour.
c. when ignited with a match in open air, paper burns
d. when heated strongly, sugar turns dark brown.
e. when treated with bleach, some dyed fabrics change color.

Asample of silver (with work function ? = 4.52 ev) is exposed to an ultraviolet light source (? = 200 nm), which results in the ejection of photoelectrons. what changes will be observed if: silver is replaced with copper (? = 5.10 ev) more photoelectrons ejected no photoelectrons are emitted fewer photoelectrons ejected more energetic photoelectrons (on average) less energetic photoelectrons (on average)

The is a particle with one unit of positive charge a. proton b. positron c. electron d. nucleus awnser quick it is a important science test!

Tin has ten stable isotopes. the heaviest, 124sn, makes up 5.80% of naturally occuring tin atoms. how many atoms of 124sn are present in 82.0 g of naturally occurring tin? what is the total mass of the 124sn atoms in this sample?