Give one property that makes copper very useful for electrical wiring?

It is a conductor of electricity, so it allows electricity to pass through it.

One of its properties is that is conductive which means electricity passes through it with minimal heat happening for example paper is a poor conductor because the paper bursts into flame when introduced to electricity. 

C₂H₆ + 2Cl₂ => C₂H₄Cl₂ + 2HCl

Or from left to right:

1, 2, 1, 2

Explanation:

To balance an equation, start by counting the number of atoms of each element on both sides.

C₂H₆ + Cl₂ => C₂H₄Cl₂ + HCl

C  2                 C  2

H  6                 H  5

Cl  2                Cl  3

We should increase the number of hydrogen atoms (H) on the right (products).

C₂H₆ + Cl₂ => C₂H₄Cl₂ + 2HCl

C  2                 C  2

H  6                 H  6

Cl  2                Cl  4

Increase the number of chlorine atoms (Cl) on the left (reactants).

C₂H₆ + 2Cl₂ => C₂H₄Cl₂ + 2HCl

C  2                  C  2

H  6                  H  6

Cl  4                 Cl  4

The equation is now balanced because there are the same number of atoms on each side.

C₂H₆ + 2Cl₂ => C₂H₄Cl₂ + 2HCl

or, if your drop down menus need you to write "1".

1C₂H₆ + 2Cl₂ => 1C₂H₄Cl₂ + 2HCl

The correct format is not to write the "1".