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(a) In a chemical reaction, the sum of the masses of the reactants and products remains unchanged. This is called ————.

(b) A group of atoms carrying a fixed charge on them is called ————.

(c) The formula unit mass of Ca_3 (PO_4)_2  is ————.

(d) Formula of sodium carbonate is ———— and that of ammonium sulphate is ————. 

Answers (1)

(a) In a chemical reaction, the sum of the masses of the reactants and products remains unchanged. This is called Law of conservation of mass.

It states that mass is neither created nor destroyed in chemical reactions.

(b) A group of atoms carrying a fixed charge on them is called ions.

An ion is a charged atom or molecule. It is charged because the number of electrons are not equal to the number of protons in the atom or molecule.

 

(c) The formula unit mass of Ca_3(PO_4)_2 is 310.

Ca_3 (PO_4)_2 = (40) 3 + [31 + (16) 4] 2 = 120 + 190 = 310

(d) Formula of sodium carbonate is  Na_2CO_3 and that of ammonium sulphate is (NH_4)_2SO_4

 

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