iPath DJ-UBS Natural Gas TR Sub-Idx (GAZ)

[flemsnopes]

(1) "explain to us what is an NAV"

Answer: Definition of 'Net Asset Value - NAV'
A mutual fund's price per share or exchange-traded fund's (ETF) per-share value. In both cases, the per-share dollar amount of the fund is calculated by dividing the total value of all the securities in its portfolio, less any liabilities, by the number of fund shares outstanding.
http://www.investopedia.com/terms/n/nav.asp#axzz1pf1FpuCp

(2)"why should GAZ trade 150% above it"

Answer: Not sure, but possibly because of the following:
http://www.cnbc.com/id/46403675

(3) "simple question"

Answer: No.