Multiple ChoiceWhich of the following is the number of protons in an atom of the element with atomic number 13?116views
Multiple ChoiceWhich of the following is the smallest chemical unit that retains the properties of a pure substance?116views
Multiple ChoiceAn atom contains 11 protons and 12 neutrons. What are its atomic number and mass number?137views
Multiple ChoiceWhich of the following is the major impurity added to silicon to create n-type semiconductors?87views
Multiple ChoiceHow many neutrons are present in an atom of cadmium (Cd) with a mass number of 112?129views