What do all of the elements in a given horizontal row of the periodic table have in common?

What element breaks down into yttrium-90?

A650 ml sodium bromine solution has a bromide ion concentration of 0.245 m. what is the mass (g) of sodium bromide in solution? a) 103.b)0.00155.c)16400.d) 16.4.e) 0.159

When a device is used in a circuit in which the voltage is 81 v the current flowing through the device is 3 a what is the resistance of the device