After 6400 years of undergoing alpha decay, a sample contains only 6.25% of the radium nuclei it initially had. What is the half-life of these radium nuclei?

What are atoms of the same element with varying number of neutrons

Which of these statements is true? a. quarks pair with leptons to form protons and neutrons. b. quarks pair with bosons to form photons. c. quarks pair with photons to form protons and neutrons. d. quarks pair with other quarks to form protons and neutrons. e. quarks pair with electrons to form protons.

Suppose a wire with a current is pushed upward by a magnetic field. how would the wire move if the direction of the current reversed? explain your answer.