Question

Fill in the blanks:
(a) Phosphorus is a very _________ non-metal.
(b) Metals are ______ conductors of heat and __________.
(c) Iron is _________ reactive than copper.
(d) Metals react with acids to produce _______ gas.

Answer 1

Phosphorus forms compounds with many elements like chlorine, oxygen etc. A characteristic property of metals is that they have free electrons in their valent shell which get aligned in presence of potential difference. Iron is above copper in the chemical reactivity series. The gas produced when metals react with acids can be identified by the pop sound that is produced when a lit match stick is brought near the test tube.

Complete step by step answer:
Phosphorus is a chemical element with the symbol P and atomic number 15 present in the 15th group of the modern periodic table.
Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus. However, phosphorus is never found as a free element in nature due to its reactivity.
Phosphorus is very reactive and will spontaneously inflame in air. This is the reason why it is stored in water.
Hence (a) Phosphorus is a very reactive non-metal.
Metals as mentioned in the hint have free electrons also referred to as free valencies in the crystal lattice. Due to close packing of metal ions, the lattice can conduct heat. On the other hand, metals can conduct electricity as there are free electrons that can move when a potential difference is applied.
Hence (b) Metals are good conductors of heat and electricity.
When an iron rod is dipped in an aqueous solution of copper sulfate, we observe that the blue color of the solution changes to green in sometime. This is because iron displaces copper ion from the solution and forms iron(II) sulfate. From this we can say that iron is more reactive than copper.
Hence (c) Iron is more reactive than copper.
Let us write the reaction of acids on metals:
$\text{Zn + 2HCl }\to \text{ ZnC}{{\text{l}}_{2}}\text{ + }{{\text{H}}_{2(g)}}$
In the above reaction we see that when an acid reacts with metal, hydrogen gas is released.
Hence (d) Metals react with acids to produce hydrogen gas.

Note: Although phosphorus is considered to be reactive in general, white phosphorus is considered to be the most reactive allotrope of phosphorus. It is commonly called a devil's element due to its eerie glow and its tendency to burst into flames when exposed to air.