What is an insulator give an example

The experiments with static charges were done by:

The atoms in a nickel crystal vibrate as harmonic oscillators with an angular frequency of 2.3 × 1013 rad/s. the mass of a nickel atom is 9.75 × 10-26 kg. what is the difference in energy between adjacent vibrational energy levels of nickel? (h = 6.626 × 10-34 j • s, , 1 ev = 1.60 × 10-19 j)

Elements in group viiia (also known as group 18, or the noble gases) have similar properties because they all have a. the same number of electron shells b. full octets c. the same number of valence electrons d. the same number of electrons needed to fill their octet