Ineed to know why dis chinese traders demand payment for their good in gold?

In order to have a trade, both partners must have goods that the other partner wants. And Europeans didn't have anything that the Chinese wanted; so they gave them gold instead.

Also, another factor that probably came into play, was when the Europeans first came to trade with the Chinese, the Chineses saw them as barbarians. Chinese also thought of themselves as the "Middle Kingdom," a place that was superior to the rest of the world. 

Therefore, they had no interest in anything that the Europeans tried to trade with them.  They would only accept gold and silver.

This later became a problem for the Europeans because this drained their reserves of gold and silver. 

This is why they eventually decided to start trading opium to the Chinese in exchange for silks, porcelains, and tea.  This led to a great deal of conflict and, eventually, the Opium Wars.

On april 20, 1814, the dethroned emperor left france for the isle of  elba, where he was exiled under the terms of the treaty of fontainebleau.napoleon  would be allowed to ruleelba, which had 12,000 inhabitants. perhaps cruelly, the treaty allowed him to retain the title "emperor."