Questions

It is a Postbox or a Mailbox which contains thousands of letters or mails or messages.

Helium has the lowest freezing point of all the elements. When coming to metals, mercury has the lowest freezing point of all the metals.

In 37 BC, Octavian became the most powerful man in the Roman Empire for 44 years under the titles of Augustus, which meant 'holy' and imperator, meaning 'Victorious general'. He also called himself Princeps, 'first citizen of the state'. The period of Roman history beginning with his rule upto A.D 284 is called the principate. His rule and the period following it were  peaceful and  are known in history as 'Pax Romana' which means 'Roman Peace'

Nigeria, an African country on the Gulf of Guinea. 

Nigeria has a Federal Republic and Presidential system of Government.