There are four sketches below. the first sketch shows a sample of substance x. the three sketches underneath it show three different changes to the sample. you must decide whether each of these changes is possible. if a change is possible, you must also decide whether it is a physical change or a chemical change. each sketch is drawn as if the sample were under a microscope so powerful that individual atoms could be seen. also, you should assume that you can see the entire sample, and that the sample is in a sealed box, so that no matter can enter or leave.

the tides are influenced by both the moon and the sun, it's easy to see that when the sun lines up with the moon and the earth, as during a new moon or full moon, the tidal effect is increased. these are known as spring tides, named not for the season, but for the fact that the water "springs" higher than normal. on the other hand, if the sun and the moon are 90 degrees apart in relation to an observer on earth as during the first quarter moon or third quarter moon, then high tides are not as high as they normally would be. this is because despite its greater distance, the sun's mass allows it to exert enough gravitational force on the oceans that it can negate some of the effects of the moon's pull. this phenomenon of lower high tides is called a neap tide. if you need more information on this topic visit moonconnection.com.

while cooking a piece of 1/2 pound beef steak, a cast iron pan (2.4kg in weight) was heated 260 celsius.