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Options (ii) and (iii) are correct because alpha particle scattering revealed a tiny, dense, positive nucleus, disproving Thomson’s model. Options (i) and (iv) are incorrect because neutrons were discovered later and deflections did not trace electron movement.
Neutral aluminium-27 has 13 electrons and 14 neutrons. Bromide ion-80 has 36 electrons and 45 neutrons. Mercury-201 ion has 78 electrons and 121 neutrons. Neutrons equal mass number minus protons and electrons account for charges.
Option (iii) is the correct answer. The assertion is true because molten ionic compounds conduct electricity, but the reason is completely false because ions are fixed in solids and mobile only in liquids.
Element B is more reactive because it needs only one electron to attain stability. Both elements are non-metals, so they share electrons to form covalent bonds, resulting in the molecular compound AB3 or PCl3.
The atomic number is 11 and mass number is 23. It is a positively charged cation because protons exceed electrons by one. Its electronic configuration is 2, 8 and the species is a sodium ion, Na+.
