Which equation shows a physical change? (1 point)

h2o(g) → h2o(s)

hcl(aq) + naoh(aq) → nacl(aq) + h2o(l)

2h2o(l) → 2h2(g) + o2(g)

pb(no3)2 (aq) + 2ki(aq) → 2kno3(aq) + pbi2(s)

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?

In order of decreasing light-transmitting capabilities of materials, which is the correct sequence? a. transparent -> translucent -> opaque b. opaque -> transparent -> translucent c. opaque -> translucent -> transparent d. translucent -> transparent -> opaque

What does the law of conservation of mass state?