Bingo! An Ri Masterclasses teaser This puzzle was used by a primary mathematics teacher and solved by a 9 year old girl. Originally posted by Mike Fletcher April 9 2017, 12:01am, in The Sunday Times (If you subscribe to the … Continue reading →
4 litres of water problem You are camping be the edge of a stream and a recipe calls for EXACTLY 4 litres of water. Unfortunately you only have two empty containers, one that holds 3 litres of water and one … Continue reading →
Bear Puzzle A bear walks 1 kilometre south, 1 kilometre west and then 1 kilometre north He ends up in exactly the same place he started. What colour is the bear?
Continue reading →The magic triangle A triangle can be made by arranging 4 shapes on a 5 x 13 grid. By re-arranging the shapes a new triangle can be made. The pieces in the lower triangle are exactly the same as those … Continue reading →
When iodine is heated what gas is evolved? When solid iodine is heated it sublimes and becomes a purple vapour. (See heating chemicals). Subliming is a physical change that describes what happens when a solid turns into a gas when … Continue reading →
Examples of acids and alkalis (see acids and alkalis) Strong acids: Hydrochloric acid, sulfuric acid, nitric acid Weak acids: Citric acid, found in lemon and lime juice; Ethanoic (acetic) acid, found in vinegar. Strong alkalis: Sodium hydroxide (caustic soda), found … Continue reading →
Does copper carbonate sublime? No. Copper carbonate will decompose (split apart) when heated releasing carbon dioxide gas and leaving copper oxide (a black powder). Colour change: Green to black. (See heating chemicals). Chemicals that do sublime include iodine and dry … Continue reading →
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