Which everyday process involves the removal of dissolved impurities from water by passing it through a bed of sand and gravel?

Which property of a magnet means it will always realign itself to point in a north-south direction if freely suspended?

Which phenomenon explains why distant mountains sometimes appear bluish in colour?

Which common acid is found in citrus fruits like lemons and oranges giving them a sour taste?

Which everyday substance when mixed with water forms a solution that conducts electricity?

Which common household acid is found in vinegar and gives it its sour taste and smell?

Which type of joint is found in the skull where bones are fixed together and allow no movement?

Which process in plants involves losing water vapour through stomata helping in cooling and nutrient transport?

Which animal group is characterised by having a backbone or vertebral column?

Which part of the plant transports water and minerals from roots to leaves and food from leaves downward?

Which animal group lacks a backbone and includes insects worms and molluscs?