Why does the number of elements vary from period to period

If two protons and two neutrons are added to the nucleus of a carbon atom, what nucleus does it become?

On an amusement park ride, riders stand inside a cylinder of radius 7.0 m. At first the cylinder rotates horizontally. Then after the cylinder has acquired sufficient speed, it tilts into a vertical plane, as shown in the diagram.

To increase power, it is necessary to decrease the work being done and decrease the time in which the work was completed. increase the work being done or decrease the time in which the work is completed.

Which are examples of bases? Check all that apply. A. Water B. Bleach C. Antacids D. Soap

Why proton doesnt repll each other in nuclous of an atom?

Which method would you use to find the volume of an irregular shaped object?

A step up transformer has a primary coil with 100 turns and a secondary coil with 25 turns if the input voltage in the primary coil is 40 volts what is the output voltage reduced to in the secondary coil A) 20 volts B) 35 volts C) 4 volts D) 10

An instrument used to measure atmospheric pressure is called a

A 200-kg boulder is 1000-m above the ground. what is its potential energy?

The law of reflection states that if the angle of incidence is 81 degrees, the angle of reflection is ___ degrees.