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SAMPLE PAPERS SCIENCE(CHEMISTRY) Q1- State the postulates of Dalton’s atomic theory Q2- Define a molecule. Q3 Define the atomic mass unit Q2-Whatis the difference between an atom and a molecule? Q3-What is the difference between molecule of an element and the molecule of a compound. 3. Which postulate of Dalton’s atomic theory can explain the law of definite proportions? Which postulate of Dalton’s Atomic Theory is the result of Law of Conservation of mass? In a reaction, 5.3 g of sodium carbonate reacted with 6 g of ethanoic acid. The products were 2.2 g of carbon dioxide, 0.9 g water and 8.2 g of sodium ethanoate. Show that these observations are in agreement with the law of conservation of mass. sodium carbonate + ethanoic acid > sodium ethanoate + carbon dioxide + water - Whatis the atomic number of chlorine ? Q2-Whatis the atomic symbol of sodium? . When 3.0 g of carbon is burnt in 8.00 g oxygen, 1 1.00 g of carbon dioxide is produced. What mass of carbon dioxide will be formed when 3.00 g of carbon is burnt in 50.00 g of oxygen? Which law of chemical combination will govern your answer? Q1. Define the atomic mass unit. Q2. Why is it not possible to see an atom with naked eyes? Q3.A 0.24g sample of compound of oxygen and boron was found by analysis to contain 0.096 g of boron and 0.144 g of oxygen. Calculate the percentage composition of the compound by weight. Q1- Differentiate between an atom and an ion. Q2 What are polyatomic ions? Give examples. Q3 Draw a table for some common simple and polyatomic ions. - List the valency of the following elements- N, C,S, Cl, Ne How is a cation different from an anion? 
