Part1: SELECT basics 

1.  Show the population of Germany.

SELECT population 
FROM world 
WHERE name = 'Germany'

2.Show the name and the population for 'Sweden', 'Norway' and 'Denmark'. 

SELECT name, population 
FROM world 
WHERE name IN ('Sweden', 'Norway' , 'Denmark')

3.Show the country and the area for countries with an area between 200,000 and 250,000.

SELECT name, area 
FROM world
WHERE area BETWEEN 200000 and 250000