You may feel cold when you touch certain kinds of matter because some matter gives off cold air. I’m NOT SURE
<u>Answer:</u> The given chemical reaction can be classified as synthesis and exothermic.
<u>Explanation:</u>
A synthesis reaction is defined as the reaction where two small chemical species combine in their elemental state to form a single large chemical species.
Exothermic reactions are defined as the reactions in which heat is released by the reaction. The heat is written on the product side of the reaction.
For the given chemical reaction:

The above chemical reaction is a type of synthesis and exothermic as two substances in their elemental state are combining. Also, heat is getting released in the reaction.
Hence, the given chemical reaction can be classified as synthesis and exothermic.
Answer:
Pressure that is exerted by one gas as if it occupied a container by itself.
Mass of PH3= 6.086 g
<h3>Further explanation</h3>
Given
6.0 L of H2
Required
mass of PH3
Solution
Reaction
P4 + 6H2 → 4PH3
Assumed at STP ( 1 mol gas=22.4 L)
Mol of H2 for 6 L :
= 6 : 22.4 L
= 0.268
From the equation, mol PH3 :
= 4/6 x moles H2
= 4/6 x 0.268
= 0.179
Mass PH3 :
= 0.179 x 33,99758 g/mol
= 6.086 g