Guess Questions 2nd Summative Assessment 2012-13 SET-01 [Chemistry] 1. Calculate number of moles in 34 g of NH3 (Given atomic mass of N= 14 u; H= 1 u)?[2] 2. Write chemical formulas of :(a) Sodium Carbonate (b)Ammonium Chloride[2] 3. (a) Write a chemical formula of a compound using zinc ion and phosphate ion. (b) Calculate the ratio by mass of atoms present in a molecule of carbon dioxide (Given C=12, O=16)[2] 4. (a) State the law of Definite proportion with an example.(b) Give any two limitations of Dalton�s Atomic Theory. [3] 5. Calculate number of atoms in 120 g of Ca :( atomic mass of Ca= 40u) [3] 6. (a)Write the symbol and name of the element having 14 protons. (b) Complete the table. Element Atomic No Mass No Proton Neutron Cl 17 - - 18 Si - 28 - - F - - 9 10 (c) Give one drawback of Rutherford model. [3] 7 .(a)The average atomic mass of a sample of an element X is 16.2u.What ...