What are defect of mendeleevs perodic table

If a || b and e || f, what is the value of y ?

What term is missing from the central region that describes hypotheses, theories, and laws? popular predictable mathematical falsifiable

Which of the following is a conclusion that resulted from ernest rutherford’s scattering experiment? (will mark brainliest) a. the nucleus is negatively charged b. the atom is a dense solid and is indivisible c. the mass is conserved when atoms react chemically d. the nucleus is very small and the atom is mostly empty space