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Hydrides of Nitrogen

Assertion :Mi...

Question

Assertion :Mixture of $C a C_{2}$ and $C a_{3} P_{2}$ placed in the container with holes is thrown into the sea, a luminous flame is produced called Holmes signal Reason: Both react with $H_{2} O$ :
$C a C_{2} + 2 H_{2} O$ $⟶$ $C a (O H)_{2}$ + $C_{2} H_{2}$
$C a_{3} P_{2} + 6 H_{2} O ⟶ 3 C a (O H)_{2} + 2 P H_{3}$
Some $P_{2} H_{4}$ is also produced, which catches fire instantly, which in turn ignites $C_{2} H_{2}$ (acetylene) and then luminous flame is produced. This guides the approaching ship. This signal is called Holme's signal.

A

Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

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B

Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

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C

Assertion is correct but Reason is incorrect

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D

Both Assertion and Reason are incorrect

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Solution

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
The spontaneous combustion of phosphine is technically used in Holme's
signals. It is also used in smoke screens. Containers containing calcium carbide and calcium phosphide are
pierced and thrown in the sea when the gases evolved burn and serve as a signal. Water enters the containers through the bottom and and reacts to give acetylene and phosphine (and some $P_{2} H_{4}$ ). Phosphine (and some $P_{2} H_{4}$ ) gets ignited spontaneously as it comes in contact with air and also ignites acetylene. Thus a bright red flame is produced which is accompanied by huge smoke due to the burning of phosphine. This serves as a signal to the approaching ships.
The balanced chemical reactions are as shown.
$C a C_{2} + 2 H_{2} O$ $⟶$ $C a (O H)_{2}$ + $C_{2} H_{2}$
$C a_{3} P_{2} + 6 H_{2} O ⟶ 3 C a (O H)_{2} + 2 P H_{3}$

Option (A) is correct. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

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