Which element has properties of electrical conductivity and luster and exists as a liquid at stp?

Mercury - hydrargyrum (Hg)

Explanation:Mercury is a chemical element with the symbol Hg and atomic number 80. It is commonly known as quicksilver and was formerly named hydrargyrum.  

Symbol: Hg

Atomic number: 80

Atomic mass: 200.59 u

Melting point: -38.83 °C

Boiling point: 356.7 °C

Electron configuration: [Xe] 4d^14 5d^10 6s^2

Group :12

Ionization energy 1007.1J

Electronegativity :2

Crust Abundance : 0.085ppm

Electron Affinity : Unknown eV

Name: Mercury , the first planet in the solar system (Hg from former name hydrargyrum , from greek  hydr - water and  argyros silver .

I hope it helps. :).

wavelength variability is the right one