Question 1(multiple choice worth 4 points)

during a chemical reaction, what remains constant?

composition
temperature in beaker
amount of energy
the bonds

question 2(multiple choice worth 4 points)

(sc.912.p.8.2)

which of the following is not a physical change?

freezing ice
molding clay
filtering a mixture
cooking a steak

question 3(multiple choice worth 4 points)

the type of change where new compounds are formed is called a

chemical change
phase change
physical change
nuclear change

question 4(multiple choice worth 4 points)

(sc.8.p.9.1)

where does the energy given off by an exothermic reaction come from?

the chemicals make the energy during the reaction from atoms that are consumed.
the atoms in the air are converted to energy during the explosion.
the energy is converted from the heat taken in by the exothermic reaction.
more energy is given off by the new bonds formed than is needed to break the original bonds.

question 5(multiple choice worth 4 points)

when 10 grams of salt dissolve in 25 grams of water, what is the resulting mass of the mixture?

the resulting mass would be 15 grams.
the resulting mass would be 35 grams.
the resulting mass would be 40 grams.
the mixture would need to be measured to determine the mass.

Astone dropped into a well is heard to strike the water after 8seconds. find the depth of the well if the velocity of sound is 350m/s

(science)study the following ocean currents map. an ocean currents map is shown. on the map the locations for san diego, california and savannah, georgia are marked. there is a looping current from the north past san diego and a looping current from the south near savannah which statement is most likely correct about the average temperatures in san diego, california as compared to savannah, georgia? it is higher in savannah because of the cool ocean currents from the south. it is higher in savannah because of the warm ocean currents from the north. it is lower in san diego because of the warm ocean currents from the south. it is lower in san diego because of the cool ocean currents from the north.

An internally reversible refrigerator has a modified coefficient of performance accounting for realistic heat transfer processes of where qin is the refrigerator cooling rate, qout is the heat rejection rate, and is the power input. show that copm can be expressed in terms of the reservoir temperatures tc and th, the cold and hot thermal resistances rt,c and rt,h, and qin, as where rtot rt,c rt,h. also, show that the power input may be expressed as 1.39 a household refrigerator operates with cold- and hot-temperature reservoirs of tc 5 c and th 25 c, respectively. when new, the cold and hot side resistances are rc,n 0.05 k/w and rh,n 0.04 k/w, respectively. over time, dust accumulates on the refrigerator’s condenser coil, which is located behind the refrigerator, increasing the hot side resistance to rh,d 0.1 k/w. it is desired to have a refrigerator cooling rate of qin 750 w. using the results of problem 1.38, determine the modified coefficient of performance and the required power input w under (a) clean and (b) dusty coil conditions. internally reversible refrigerator qout qin w high-temperature reservoir low-temperature reservoir th th,i tc,i tc high-temperature side resistance low-temperature side resistance w qin th tc qinrtot tc qinrtot copm tc qinrtot th tc