Question

Nuclear mass of certain atom as 20.088 x 10 with mass no -27 kg and charge on nucleus as 9.612x 10 with mass no -19 coulombs . calculate the atomic no , mass no of element and name of element

Answer 1

answer : element is Carbon, atomic no 6 , mass no 12

given, nuclear mass of certain atom, m = 20.088 × 10^-27 kg

charge on nucleus , Q = 9.612 × 10^-19 C

we know, in nucleus of an atom, protons and neutrons are present. but only protons do have charge. let number of protons = n

so, charge on n protons = charge on nucleus of the atom

⇒n × 1.602 × 10^-19 = 9.612 × 10^-19

⇒n = 9.612/1.602 = 6

hence number of protons = 6

so, atomic number = number of protons = 6.

now nuclear mass = mass of protons + mass of neutrons

⇒ 20.088 × 10^-27 kg = 6 × 1.6726 × 10^-27 + no of neutrons × 1.6749 × 10^-27 kg

⇒20.088 = 6 × 1.6726 + no of neutrons × 1.6749

⇒20.088 - 10.0356 = no of neutrons × 1.6749

⇒10.0524 = no of neutrons × 1.6749

⇒no of neutrons = 10.0524/1.6749 ≈ 6

so, mass no = no of protons + no of neutrons

= 6 + 6 = 12

element is not other than carbon.