5. Give reasons.
(c) Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not.
Paper has a low ignition temperature and hence catches fire easily. But when it is wrapped around an aluminium pipe, heat is transferred to the metal and hence the ignition temperature of the paper is not reached. That is why paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not.
Paper by itself catches fire easily because it has low ignition temperature but when wrapped around an aluminium pipe paper's ignition temperature isn't attained. This is due to aluminium metal absorbing the heat supplied to paper. So, it does not catch fire easily.