The graph (Fig. A) illustrates the correlation between the number of protons (x-axis) and the number of neutrons (y-axis) for elements A, B, C, D, and E in the periodic table. These elements are denoted by the letters rather than their conventional symbols.

(a) Identify the radioactive radiation emitted when element C decays into element E. Represent this using a nuclear reaction.

(b) What is the special name given to elements D and E?

(c) If element C transforms into element B by emitting a radioactive ray, how will this ray behave in an electric field?

(a) From the graph,

Number of proton in C = 92

Number of neutron in C = 146

Mass number of C = Number of proton in C + Number of neutron in C = 92 + 146 = 238

Number of proton in E = 93

Number of neutron in E = 145

Mass number of E = Number of proton in E + Number of neutron in E = 93 + 145 = 238

Since element C has one excess proton and one neutron less than the element E so if C decays into E then it's proton number increases by one and neutron number decreases by one keeping the mass number same which is only in case of beta radiation.

Thus, reaction will as follow :

²³⁸₉₂C → ²³⁸₉₃E + ⁰_-1β

(b) As points D and E are situated on the same vertical line but on different horizontal lines it means they have same number of protons but different number of neutrons i.e., their atomic number is same but mass number is different so they are isotope of each other.

(c) Number of protons in B = 90

Number of neutron in B = 144

Mass number of B = Number of proton in B + Number of neutron in B = 90 + 144 = 234

As, element B has two protons less than element C and has mass number four less than C during a decay of C into B two protons and two neutrons emit which is nothing but an alpha particle.

Alpha particles shift towards negative plate in an electric field.