1.2 g of marble containing sand as the only impurity is dissolved in 50 em' of HCl of concentration I mol. dm! The excess acid is neutralised by exactly 27.5 cm of a (10) solution of sodium hydroxide of concentration 1 mol. dm. Calculate the percentage CaCO, in the impure marble.​

20) what is a magnetic field? 21) in which direction do magnetic field lines always point? 22) sketch a diagram showing how a plotting compass points around a 23) name two magnetic poles that will: a) attract each other b) repel each other. 24) explain why you can use a compass to navigate. 25) what's an electromagnet? 26) list two ways to increase the strength of an electromagnet. 27) the wire in a simple motor feels a force when a current flows through it. why is this? i need answers to check mine