Assertion :Mixture of
CaC2 and
Ca3P2 placed in the container with holes is thrown into the sea, a luminous flame is produced called Holmes signal Reason: Both react with
H2O :
CaC2+2H2O ⟶ Ca(OH)2 + C2H2
Ca3P2+6H2O⟶3Ca(OH)2+2PH3
Some P2H4 is also produced, which catches fire instantly, which in turn ignites C2H2 (acetylene) and then luminous flame is produced. This guides the approaching ship. This signal is called Holme's signal.