1) Plastic is melted and injected into a mold
2) Protein is digested in the stomach
3) A coal-fired power plant produces gases that cause acid rain
4) Dry ice sublimes into the air
2007-01-26 16:45:23 · 6 answers · asked by theweirdguy1 2 in Science & Mathematics ➔ Chemistry
1 is a change in state, from solid to liquid.
2 and 3 are chemical reactions
4 is also a change in state from solid to gas.
Since 1 and 4 are physical changes, only 2&3 are correct.
2007-01-26 16:52:18 · answer #1 · answered by scphelps3 2 · 0⤊ 0⤋
Chemical changes are 2 and 3 only. proteins in the stomach are converted to smaller protein units. The coal in a power plant is burned (thus chemically reacted) to form gases including SO2 which is a component of acid rain.
For 1 and 4, it is physical change. Melting, freezing and sublimating involves just rearragement of the molecules not breaking or creation of bonds in the molelcule.
2007-01-27 00:55:36 · answer #2 · answered by Aldo 5 · 0⤊ 0⤋
2, 3 and 4
2007-01-27 00:50:00 · answer #3 · answered by nickname 4 · 0⤊ 2⤋
No.2 & 3 are chemical changes while 1&4 are physical changes
No.2 is also called biochemical change.
2007-01-27 00:55:37 · answer #4 · answered by smith j 2 · 0⤊ 0⤋
2 and 3 are chemical changes
1 and 4 are only physical changes and can be reversed.
2007-01-27 00:54:52 · answer #5 · answered by sandy 2 · 0⤊ 0⤋
2 and 3
1 and 4 are physical changes
2007-01-27 00:52:55 · answer #6 · answered by Alan S 3 · 0⤊ 0⤋