How many neutrons does element X have if its atomic number is 24 and its mass number is 99?

If element X has 31 protons, how many electrons does it have?

If i could choose to control fire or water i would rather control

A train engineer drives a train 235 km north along a straight track. Then he drives the train back south 126 km. Finally, he drives north again 45 km to his final destination. What is the engineer's total magnitude of its displacement?

You stand on a bridge above a river and drop a rock into the water below from a height of 53 m. What is the acceleration of the rock as it falls

In a series RCL circuit the generator is set to a frequency that is not the resonant frequency. This nonresonant frequency is such that the ratio of the inductive reactance to the capacitive reactance of the circuit is observed to be 5.68.

What does a fern ultimately depend on as an energy source?

According to the Doppler Effect, which statement is true about a sound as it approaches you and then moves away. A) As the source approaches you, the sound waves are compressed so the pitch of the noise increases.

If you have a beam perfectly balanced on a fulcrum and put a weight at the very end of one side, is there a way to know where you should put a heavier object on the other end?

Most of the Earth's volcanoes occuWhen fossils or minerals form, certain unstable elements are sometimes locked into them.

a man is standing on the edge of a 20.0m high cliff. he throws a rock vertically with an initial velocity of 10.0m/s. how high does the rock go?