In a neutral atom, the number of protons is equal to the number of electrons.
Given that the charge on the ion of the element is -1. This means that there is one electron more than the number of protons in the element.
The atomic number = Number of protons = 57 -1 = 56
Element with atomic number 56 is Barium.
Mass number of the element = Number of protons + Number of neutrons
= 56 + 80 = 136
So the identity of the species: 
a) They are solid at ambient temperatures of 25 ° C and pressure of 1 atm.
b) Ionic compounds represent high temperature melting and boiling.
c) They are hard and brittle and then subjected to the impact, break easily, creating planar faces.
d) When dissolved in water, or pure liquid, carry electrical current due to the existence of ions that move freely and can be attracted by the electrodes, closing the electric circuit.
<span>e) His solvent is water. </span>
A mole is the assemblage of 6.022×10^23 ions.This number is also known as Avogadro Number.
Avogadro constant=6.022×10^23 mol^-1
Answer:
Cutting the supply of oxygen
Explanation:
We know that a thing need three things to burn
- Oxygen
- Heat
- flammable object .
Co_2 stops oxygen supply so fire gets extinguished
