A certain element has 2 isotopes, one having a mass of84.9118 amu and a fractional abundance of 72.15 % and the otherhaving a mass of 86.9092 and a fractional abundance of 27.85%. Calculate the atomic weight of this element.

(b) (i) Differentiate between empirical formula and molecular formula

(ii) A compound has the percent composition 80.0% Cand 20.0% H. Calculate its empirical formula.

(c) (i) Give the general reaction of Group 2A elements with water. [3marks]

(ii) Discuss the trends observed with each element in Group2A. [3marks]

(d) Alkali metals react rapidly with oxygen, but they give different kinds of products.

Give the specific type of oxides formed by these metals.

Complete and balance the following equations:

(i) NaOH(aq) + NH4Cl(aq)____________________________________

(ii) NaHCO3(aq)+ HCl(aq)___________________________________________

(iii) CuCO3(aq)+ H2SO4(aq) __________________________________________

(iv) HCl(aq)+ Na(s)_______________________________________________

(v) HCl(aq) + NaOH(aq)