1a) Atomicity is the number of atoms in a molecule of an element 1aii) Mass number of an element is the sum of the proton number and the neutron number 1aiii) Isotopy is the existence of atom of the same element that have the same atomic number but different mass number 1bi) The reaction is a displacement reaction because Zinc will displaced hydrogen from hydrochloric acid because it is above hydrogen in the activity series. There is an effervescence & hydrogen gas is given off the gas is collected over water because it is insoluble in water Zn + Hcl ----------- Zncl2 + H20 1bii) It is used in filling ballons because it has a low density * it is used in hardening Fat and oils in the manufacture of margine and other solid fats * it is used in the manufacture of ammonia in the harber process 1c) Molar mass of HNO3 = 1 + 14 + (16)3 = 63g/mol % of oxygen = (16)3/63 x 100% = 76.19% 1d) * copper * iron * Tin * Aluminium 1e) * Sodiumtetrahy-droxozinate(ii) --------- Na2Zn(OH)4 * sodiumoxonitrate(iii) --------- NaNo2 1eii) Used in soap making * used to soften hard water * used as fertilizer * sodium chloride is used as preservative for meat and fish