Junior Science Olympiad Olympiad Junior Science — practice questions
66 free MCQs with worked solutions. Tap any question for the answer + explanation, or practice them all in the app.
Practice Junior Science Olympiad Olympiad Junior Science in the app →A student dips blue litmus paper in lemon juice and it turns red. The juice is:Red litmus paper dipped in a bitter tasting solution turns blue. The solution is a:A teacher calls litmus and turmeric natural indicators. Methyl orange is instead a:Onion and vanilla change smell in acids and bases. Such indicators are called:Zinc granules are dropped into dilute sulphuric acid. The gas that bubbles out is:A metal reacts with an acid. Besides hydrogen gas, the other product is a:Dilute acid is poured on sodium carbonate. The gas released turns lime water milky. It is:Hydrochloric acid is added to sodium hydroxide until the pink colour goes. The reaction is:Copper oxide dissolves in hydrochloric acid giving a salt and water, so metal oxides are:A mixture of several indicators showing different colours at different acidities is the:The scale that measures hydrogen ion concentration in a solution is called the:Pure water is tested with universal indicator paper. Its pH reads:A solution shows a pH of 3 on the paper. The solution is:As the hydronium ion concentration in a solution rises, the pH value:Hydrochloric acid gives far more hydrogen ions than acetic acid at equal strength. So it is a:A doctor notes the human body works only within a narrow pH range, roughly:Rain water is tested and its pH is below 5.6. This rainfall is called:Tooth enamel begins to corrode once the pH inside the mouth falls below:A dentist suggests a basic toothpaste after meals because it will:A bee sting leaves acid in the skin. Rubbing on baking soda helps because it is a mild:Blue copper sulphate crystals turn white on heating. The molecules driven off are:A doctor sets a fractured arm with a white powder that hardens with water. It is:A sealed flask is weighed before and after a reaction inside it. The total mass:Water from a river, a well and a tap all give hydrogen and oxygen in the mass ratio:Decomposing 9 g of water always gives 1 g of hydrogen and how much oxygen?Nitrogen and hydrogen in ammonia are always present in a mass ratio of:The law of definite proportions was first stated by the chemist:The atomic theory explaining both laws of chemical combination was given by:According to Dalton, the tiny particles that take part in chemical reactions are:Dalton's postulate that atoms cannot be created or destroyed explains the law of:Dalton held that atoms of one element are identical in mass and in their:Dalton said atoms combine to make compounds in ratios that are:Later work showed Dalton was wrong about one point, because atoms are made of:Since 1961 the standard reference chosen for measuring atomic masses has been:One atomic mass unit is defined as a mass equal to what share of a carbon 12 atom?The combining capacity of an element, which tells how its atoms link up, is its:A group of atoms carrying a charge, such as sulphate, is called a:Adding up the atomic masses of every atom in a molecule gives its:Hydrogen has atomic mass 1 u and oxygen 16 u. The molecular mass of water is:Using H as 1, N as 14 and O as 16, the molecular mass of nitric acid works out to:For sodium chloride, whose particles are ions, chemists calculate the:With Na as 23 and Cl as 35.5, the formula unit mass of common salt is:The SI unit used for the amount of a substance is the:One mole of any substance contains how many particles, to four figures?An electrical signal in a nerve cell starts at the dendrite and travels along the:The tiny gap between the end of one neuron and the next one is called a:The tissue built from a network of neurons and specialised for conducting signals is:A boy pulls his hand from a flame before he even thinks. The pathway used is a:Reflex arcs are formed in which part of the body?The brain and the spinal cord together make up the:Cranial nerves and spinal nerves together form the:The human brain is divided into how many major regions?The main thinking part of the brain, with regions for hearing and sight, is the:Actions we cannot control by thinking are handled by the mid brain and the:The part of the brain that gives precision to voluntary actions and keeps balance is the:The leaves of the sensitive plant fold at a touch, yet the plant has no:A shoot on a windowsill bends towards the light. This directional growth is:Roots grow down and shoots grow up in answer to the pull of the earth. This is:A pollen tube grows towards an ovule. This directional growth is an example of:When light falls on one side of a shoot, auxin gathers on the:The plant hormone that promotes cell division is:The plant hormone that signals growth to stop, such as in wilting, is:A student is startled by a loud noise and her heart races. The hormone released is:Iodised salt is recommended because iodine lets the thyroid gland make:A person lacking iodine may develop a swollen neck. This condition is:A patient with diabetes is given injections of the hormone: