The number of protons or atomic number is reduced to 2 by which form of radioactive decay?
- Beta-decay
Gamma decay
- Alpha decay
- None of the above
The Correct Option is C
Solution and Explanation
- Alpha decay: In this type of decay, the nucleus emits an alpha particle, which consists of 2 protons and 2 neutrons. As a result, the atomic number decreases by 2, and the mass number decreases by 4. This is the only type of decay among the given options that causes the atomic number to be reduced by 2.
- Beta-decay: This process involves the conversion of a neutron into a proton or vice-versa, resulting in the emission of a beta particle (electron or positron). It changes the atomic number by ±1, not by 2.
- Gamma decay: This is the release of excess energy from an excited nucleus in the form of gamma rays. It does not change the atomic number or mass number.
- None of the above: This option is incorrect because alpha decay accurately fits the criteria.
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Concepts Used:
Atom Structure Models
The three atomic models are as follows:
Thomson model:
Thomson atomic model was proposed by William Thomson in the year 1900. This model explained the description of an inner structure of the atom theoretically. It was strongly supported by Sir Joseph Thomson, who had discovered the electron earlier.
Thomson assumed that an electron is two thousand times lighter than a proton and believed that an atom is made up of thousands of electrons. In this atomic structure model, he considered atoms surrounded by a cloud having positive as well as negative charges. The demonstration of the ionization of air by X-ray was also done by him together with Rutherford. They were the first to demonstrate it. Thomson’s model of an atom is similar to a plum pudding.
Rutherford’s Alpha Scattering Experiment:
Rutherford’s conducted an experiment by bombarding a thin sheet of gold with α-particles and then studied the trajectory of these particles after their interaction with the gold foil.
Bohr’s Model of an Atom:
Bohr model of the atom was proposed by Neil Bohr in 1915. It came into existence with the modification of Rutherford’s model of an atom. Rutherford’s model introduced the nuclear model of an atom, in which he explained that a nucleus (positively charged) is surrounded by negatively charged electrons.