What does the law of conversation of mass say? how can you know whether a chemical equation is in accordance with this law?

True or false when elements combine to form a mixture, the resulting chemical properties may be very different from those of the elements that make it.

Yvette hangs a 2.4kg bird feeder in the middle of a rope tied between two trees. the feeder creates a tension of 480 n in each side of the the rope.

There are two-speed cameras, one in an are where the speed limit is 30 km/h and another where the speed limit is 50 km/h. in which will there be a smaller time interval between the photographs? explain your answer.