Ans: Average atomic mass of naturally occurring copper = (53 x 69.2)/00 + (65 x 30.8)/100
Ans: Atomicity may be defined as number of atoms present in one molecule. For example N2 is diatomic; P4 is tetra atomic in nature.
Atomic Mass of an atom is the sum of proton and neutron in the nucleus. For example the atomic mass of sodium is 23 because it contain 11 proton and 12 neutron.
Q.To weight BaCl2 or Na2SO4
Ans: For this use a watch glass and physical balance.
Q. what is the distribution of electrons in an atom of Phosphorus and how can it have two valencies
Ans: phosphorus has large atomic size and therefore posses excess electron bearing capacity in its shell, therefore it can share 3 electrons and 5 electrons to form trivalent and penta valent compounds.
Atomic number of phosphorus is 15, therefore the electronic configuration is 2 10 5
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