Sodium hydroxide (naoh) was added to pure water (h2o). which most likely were the ph values of the water before and after the sodium hydroxide was added to it?
a. before = 7, after = 9
b. before = 7, after = 4
c. before = 4, after = 7
d. before = 9, after = 7

Copper has free electrons per cubic meter. a 71.0-cm length of 12-gauge copper wire that is 2.05 mm in diameter carries 4.85 a of current. (a) how much time does it take for an electron to travel the length of the wire? (b) repeat part (a) for 6-gauge copper wire (diameter 4.12 mm) of the same length that carries the same current. (c) generally speaking, how does changing the diameter of a wire that carries a given amount of current affect the drift velocity of the electrons in the wire?

The star betelgeuse is about 600 light-years away. if it explodes tonight, a. we'll know because debris from the explosion will rain down on us from space. b. we'll know it immediately because it will be brighter than the full moon in the sky. c. we won't know about it until 600 years from now. d. none of the above.

During a car accident, a 125kg driver is moving at 31m/s and in 1.5s is brought to rest by an inflating air bag. what is the magnitude of the change in momentum to the driver