The CRC Handbook, a large reference book of chemical and physical data, lists two isotopes of europium (). The atomic mass of 47.81% of europium atoms is 150.920 u. Through a typographical oversight, the atomic mass of the second isotope is not printed. Calculate that atomic mass, taking the tabulated atomic mass of europium as 151.964 u.

Two people each hold the end of a rope and create waves by moving their arms up and down. this wave is best classified as a transverse wave because a) both the rope particles and the wave are moving in the same direction. b) the wave is moving up and down as the particles of the rope move horizontally. c) the wave is moving horizontally as the particles of the rope move up and down. eliminate d) the wave is moving in a parallel direction with the motion of the person's arms.