Q4 of 25 Page 39

How many atoms are present in a:

(i) H2S molecule, and


(ii) PO3-4 ion?

(i) There are three atoms in a H2S molecule. Two hydrogen atoms and one sulphur.

(ii) There are five atoms present in a PO4-3 ion. One phosphorus atom and four oxide ions.


More from this chapter

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2

Write down the names of compounds represented by the following formulae:

(i) Al2(S04)3


(ii) CaCl2


(iii) K2S04


(iv) KN03


(v) CaC03

 3

What is meant by the term chemical formula?

 1

Calculate the molecular masses of H2, O2, Cl2, C02, CH4, C2H6, C2H4, NH3, CH30H (Atomic masses: H = 1; 0 = 16; Cl = 35.5; C = 12; N = 14)

 2

Calculate the formula unit masses of ZnO, Na2O, K2C03

(Given: Atomic masses of Zn = 65 u; Na = 23 u; K = 39 u; C = 12u and O = 16 u)