Below is a data table from an experiment in which an effervescent tablet is added to a test tube of water, producing a solution that fizzes and releases gas bubbles. The total mass of the substances and the test tube were recorded before and after the tablet was added to the test tube of water. If matter is always conserved, how do you explain these results? Experimental Results Materials used Mass Before Reaction Mass After Reaction test tube + effervescent tablet + 10 mL water 36.55g 35.95g

You have two photos of a person walking. one shows the person at the corner of third and main streets, the other shows the person at the corner of tenth and main streets. there are lampposts at every corner in this town, and the first picture shows it to be 10: 32: 00 exactly. the second picture shows it to be 10: 49: 30. you know three facts: (1) all of the clocks are synchronized; (2) there are exactly 12 equal-sized blocks per kilometer in this town; and (3) the streets that cross main in this area are numbered consecutively, with no interruptions. what is the person’s average speed in kilometers per hour?