Q22 of 75 Page 81

Write the chemical formulae and names of the compounds formed by the following ions:

(i) Cr3+ and SO42–


(ii) Pb2+ and NO3–


(iii) Mg2+ and CO32–

(i) Cr3+ and SO42-


By applying criss-cross method:



Chemical formula: Cr2(SO4)3


Name of the compound: Chromium sulphate


(ii) Pb2+ and NO3–


By applying criss-cross method:



Chemical formula: Pb(NO3)


Name of the compound: Lead nitrate


(iii) Mg2+ and CO32–


By applying criss-cross method:



Chemical formula: MgCO3


Name of the compound: Magnesium carbonate


More from this chapter

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20

The symbols of some of the ions are given below

Na+, Mg2+, H+, Cl–, S2–


Using this information, find out the formulae of


(i) sodium carbonate


(ii) magnesium chloride


(iii) hydrogen sulphide

 21

Write the chemical formulae of Nitrates (NO3–) of Na+, K+, Al3+, Mg2+, Ca2+, Zn2+.

 23

In a chemical compound calcium sulphate:

(i) Identify the two ions.


(ii) Write the chemical formula of compound formed when positive ion is replaced by sodium ion.


(iii) Name the resulting compound.

 24

(i) Calculate the formula unit mass of Na2CO3.

[given atomic mass of Na = 23 u, C = 12 u and O = 16 u]


(ii) What is the mass of one mole of oxygen atoms?


(iii) Convert 12g of oxygen gas into mole, if atomic mass of oxygen is 16 u.