1. What is the relative atomic mass (Aᵣ) of a helium atom?

Question 1 of 9

2. To determine the formula of a metal oxide by combustion, magnesium is heated in a crucible. Why is a lid used?

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3. How many electrons in the outer shell of group 2 elements?

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4. What is meant by the term molecular formula?

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5. An oxide of nitrogen contains 26% nitrogen and 74% oxygen and has a relative molecular mass of 108. Find the empirical and molecular formulae for the oxide.

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6. A sample of bromine contained the two isotopes in the following proportions: bromine-79 = 50.7% and bromine-81 = 49.3%. Calculate the relative atomic mass of bromine

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7. What are the three subatomic particles?

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8. Calculate the relative formula mass(Mr) of cobalt chloride crystals (CoCl₂.6H₂O)

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9. Tungsten has the chemical symbol W. Suggest the chemical name of WO₃.

Question 9 of 9