Which element contains only one proton and one neutron among the following?
Deuterium
The atomic number gives the number of protons and the mass number gives protons + neutrons. Hydrogen (atomic number 1) has three isotopes, all with one proton: protium \({}^{1}_{1}\text{H}\), deuterium \({}^{2}_{1}\text{H}\) and tritium \({}^{3}_{1}\text{H}\).
Deuterium has mass number 2, so it has 1 proton and 2 – 1 = 1 neutron. Strictly, deuterium is not a separate element but an isotope of hydrogen; among the given species, however, it is the only one with exactly one proton and one neutron.
Protium has 1 proton and 1 – 1 = 0 neutrons, and tritium has 1 proton and 3 – 1 = 2 neutrons. Helium \({}^{4}_{2}\text{He}\) has 2 protons and 2 neutrons.
Hence, Deuterium.
Similar Questions
Consider the following statements regarding Thomson's model of an atom.
Statement I: The atom is a sphere of positive charge with electrons scattered inside it.
Statement II: Thomson's model could explain the presence of the nucleus in an atom.
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Important Questions from Structure of Atom
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Which of the following electron transition in hydrogen atom will require largest amount of energy?
A species having 8 electrons in the third shell is very reactive while the other species having 8 electrons in the third shell is very inactive they are :
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