Answer:

Explanation:
Half reaction:
(1)
balance: 
(2)H and O balance in acidic medium:
(3) charge balance:
Hence balanced half-reaction:
K₂CrO₄(aq) + Ba(NO₃)₂(aq) = BaCrO₄(s) + 2KNO₃(aq)
2K⁺ + CrO₄²⁻ + Ba²⁺ + 2NO₃⁻ = BaCrO₄ + 2K⁺ + 2NO₃⁻
spectator ions: K⁺, NO₃⁻
Ionic bond is formed due to the transfer of electrons from one atom to another so that all atoms involved in the bond would become stable (with 8 electrons in the outermost level)
Now, for bromine, it has 35 electrons. This means that bromine has 7 valence electrons in the outermost level. Therefore, bromine needs to gain one electron in order to become stable.
Bromine can react with elements from:
group 1: each element in group 1 needs to lose one electron to become stable. Therefore, one bromine atom can form an ionic bond when combined with an atom of an element from group 1 (element in group 1 loses its electron for bromine atom).
group 2: each element in group 2 needs to lose two electrons to become stable. Therefore, two bromine atoms can form ionic bonds when combined with an atom of an element from group 2 (element in group 2 loses two electrons, one for each bromine atom).
group 3: each element in group 3 needs to lose three electrons to become stable. Therefore, three bromine atoms can form ionic bonds when combined with an atom of an element from group 1 (element in group 3 loses three electrons, one for each bromine atom).
Since no choices are given , I cannot tell the exact choice. But the correct one would be the element from either group 1 , 2 or 3.
Answer:
When a substance is cooled, its internal energy decreases: the movement of its particles decreases. bonds between particles form when a substance condenses or freezes, or sublimes to form a solid from a gas. What is called energy? Energy is the capacity of a physical system to do work.
Explanation: