Questions

A large underground economy results in an Overstated GDP. The underground economy is also called as Black market. It refers to illegal economic activity. Transactions in the underground economy are illegal either because the good or service being traded is illegal or because an otherwise licit transaction does not comply with government reporting requirements.

Wide-mouth frog is the simplest known key distribution center (KDC) authentication protocol

In Germany, Kaiser means 'Emperor'. On 18th January, 1871 Wilhelm I was declared as Kaiser of Germany.

Norway is called as the land of midnight sun.

Yes, it can be used, if an accurate clock frequency  is not required. also the component cost is low compared to LC or Crystal.