4.What did J. J. Thomson observe when he applied electric voltage to a cathode ray tube in his famous experiment?
A.The stream of cathode ray particles was moving very slowly.
B.The glass opposite of the negative electrode started to glow.
C.The electric voltage had little effect on the stream of particles.
D.The tube contained two pieces of metal that served as electrodes.
11.The table below gives the data that is needed to calculate the average atomic mass of element B.
B-10(Isotope), 10.01(Atomic mass), 19.91(Relative abundance %)
B-11(Isotope), 11.01(Atomic mass), 80.09(Relative abundance %)
A.The stream of cathode ray particles was moving very slowly.
B.The glass opposite of the negative electrode started to glow.
C.The electric voltage had little effect on the stream of particles.
D.The tube contained two pieces of metal that served as electrodes.
11.The table below gives the data that is needed to calculate the average atomic mass of element B.
B-10(Isotope), 10.01(Atomic mass), 19.91(Relative abundance %)
B-11(Isotope), 11.01(Atomic mass), 80.09(Relative abundance %)