2-A
1-B
5-C
4-D
3-E
I hope this helped:)
You start by diving each quantity given by the atomic wight of each element:
Phosphorus (P) 
Hydrogen (H) 
Then you divide by the lowest number:
for phosphorus
for hydrogen
So the empirical formula will be:

Answer:
group 17 the halogen.as it has 7 electron in its outermost ring
Answer:
The given statement - The main criterion for sigma bond formation is that the two bonded atoms have valence orbitals with lobes that point directly at each other along the line between the two nuclei , is <u>True.</u>
Explanation:
The above statement is correct , because the sigma bond is produced by the head on overlapping, the orbitals should all point in the same direction.
<u>SIGMA BONDS -</u> Sigma bonds (bonds) are the strongest type of covalent chemical bond in chemistry. They're made up of atomic orbitals that collide head-on. For diatomic molecules, sigma bonding is best characterized using the language and tools of symmetry groups.
Head-on overlapping of atomic orbitals produces sigma bonds. The concept of sigma bonding is expanded to include bonding interactions where a single lobe of one orbital overlaps with a single lobe of another. Propane, for example, is made up of ten sigma bonds, one for each of the two CC bonds and one for each of the eight CH bonds.
Hence , the answer is true .
Answer:
Option D is correct.
The concentrations of both PCl₅ and PCl₃ are changing at equilibrium
Explanation:
Chemical equilibrium during a reversible chemical reaction, is characterised by an equal rate of forward reaction and backward reaction. It is better described as dynamic equilibrium.
This is because, the concentration of the elements and compounds involved in the reversible chemical reaction at equilibrium changes, but the rate of change of the reactants is always equal to the rate of change of products.
Hence, the concentration of reactants and products, such as PCl₅ and PCl₃ are allowed to change at equilibrium, but alas, the rate of forward reaction must always match the rate of backward reaction for the process to remain in a state of Chemical equilibrium.
Hope this Helps!!!