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Explore 22 free Olympiad Junior Science questions in Olympiad (Class 9) Chemistry. Each question opens with answer choices, the correct answer and a worked solution.
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Showing questions 1–22 of 22.
A sealed flask is weighed before and after a reaction inside it. The total mass:Read the answer and worked solution →Water from a river, a well and a tap all give hydrogen and oxygen in the mass ratio:Read the answer and worked solution →Decomposing 9 g of water always gives 1 g of hydrogen and how much oxygen?Read the answer and worked solution →Nitrogen and hydrogen in ammonia are always present in a mass ratio of:Read the answer and worked solution →The law of definite proportions was first stated by the chemist:Read the answer and worked solution →The atomic theory explaining both laws of chemical combination was given by:Read the answer and worked solution →According to Dalton, the tiny particles that take part in chemical reactions are:Read the answer and worked solution →Dalton's postulate that atoms cannot be created or destroyed explains the law of:Read the answer and worked solution →Dalton held that atoms of one element are identical in mass and in their:Read the answer and worked solution →Dalton said atoms combine to make compounds in ratios that are:Read the answer and worked solution →Later work showed Dalton was wrong about one point, because atoms are made of:Read the answer and worked solution →Since 1961 the standard reference chosen for measuring atomic masses has been:Read the answer and worked solution →One atomic mass unit is defined as a mass equal to what share of a carbon 12 atom?Read the answer and worked solution →The combining capacity of an element, which tells how its atoms link up, is its:Read the answer and worked solution →A group of atoms carrying a charge, such as sulphate, is called a:Read the answer and worked solution →Adding up the atomic masses of every atom in a molecule gives its:Read the answer and worked solution →Hydrogen has atomic mass 1 u and oxygen 16 u. The molecular mass of water is:Read the answer and worked solution →Using H as 1, N as 14 and O as 16, the molecular mass of nitric acid works out to:Read the answer and worked solution →For sodium chloride, whose particles are ions, chemists calculate the:Read the answer and worked solution →With Na as 23 and Cl as 35.5, the formula unit mass of common salt is:Read the answer and worked solution →The SI unit used for the amount of a substance is the:Read the answer and worked solution →One mole of any substance contains how many particles, to four figures?Read the answer and worked solution →
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