The answer to this question is HBr
The symbol : 
<h3>Further explanation
</h3>
There are two components that accompany an element, the mass number and atomic number
Atoms are composed of 3 types of basic particles (subatomic particles): <em>protons, electrons, and neutrons
</em>
The Atomic Number (Z) indicates the number of protons and electrons in an atom of an element.
Atomic number = number of protons = number of electrons ⇒ neutral number
Atomic mass is the sum of protons and neutrons
Atomic Number (Z) = Atomic mass (A) - Number of Neutrons
The element has 71 electrons and a charge of +1 , so
Number of protons = 71 + 1 = 72
Number of protons = the atomic number = 72
The element with atomic number 72 is Hafnium(Hf)
The atomic mass of Hf = 178 g/mol
The correct answers :
It increases with a decrease in the concentration of H₂(g).
It decreases with an increase in the concentration of S₂(g).
It decreases with an increase in the concentration of H₂(g).
<h3 /><h3>Further explanation</h3>
Forward reaction : rate to form product
In equilibrium :
The product decreases ⇒ system will move from left to right(forward reaction)
The product increases ⇒ system will move from right to left(reverse reaction)
<span>A. potassium sulfide</span>
The number of Fe atoms within a single FeCl2 molecule are one.
Explanation:
Metallic iron produces only ferrous chloride (FeCl2) on treatment with hydrochloric acid. Hydrogen gas is also liberated as the other product. But when iron is heated with chlorine gas, ferric chloride (FeCl3) is formed.
Total number of atoms within a single FeCl2 molecule are 3 atoms.
The number of Fe atoms in FeCl2 molecule are one.
Number of Cl atoms in FeCl2 molecule are two.
