How can variation and evolution affect a species' survival in an ecosystem? Explain your reasoning in 4 complete sentenced

Iknow #2 is d. i just need to know why

When a beta particle is emitted, the mass number of the nucleus a. decreases by one b. increases by one c. remains the same d. decreases by two

Which statement is true about the model of the electromagnetic spectrum a: it change the frequencies of light. b: it compare wavelengths of light. c: the color of light waves can be changed using the model. d: the intensities of light waves can be decreased using the model.