Почему для получения хлороводорода берут не раствор хлорида натрия, а кристаллическую соль и концентрированную, а не разбавленную серную кислоту?

Read and decide if the statements are true, false or nothing is known from the text

Maps were made long before reading and writing were invented. The earliest map that we know of is a cave painting on the Lascaux caves in France. The painting shows a part of the summer night’s sky 16500 years ago. Modern astronomers can still understand the night sky shown in the map. A four thousand year old map made by the Ba¬bylonians is still in existence. Many ancient map-makers thought that the world was flat, but explorers like Magel¬lan in the 15th century sailed around the world and helped to make better maps. Besides, measurements taken by satel¬lites show that our planet Is slightly pear-shaped. Satellites have also provided more accurate Information and have helped to see and map parts of the world that were lit¬tle known or never seen by humans before. Satellites have photographed the Amazon rainforest and have shown that the area the size of twenty football pitches is being cut down every minute. Pictures taken from space have also shown that one of the world's largest areas of inland water, the Aral Sea, has been shrinking very quickly. Modern satel¬lite maps show the effects of global warming and pollution and help us to understand the world around us better. More and more drivers nowadays rely on satellite navigation in their cars so the traditional road maps may not be around much longer.
11. Writing was invented a long time after the first map was drawn.
A) True B) False C) Not known
12. The first map was a map of the night sky.
A) True B) False C) Not known
13. The first map was made by the Babylonians.
A) True B) False C) Not known
14. Babylonian map-makers were very rich men.
A) True B) False C) Not known
15. Magellan's explorations helped the map-makers to Im¬prove their maps.
A) True B) False C) Not known
16. Our planet is a perfect sphere.
A) True B) False C) Not known
17. Modern maps are more detailed and accurate.
A) True B) False C) Not known
18. The Amazon rainforest is gradually disappearing. 
A) True B) False C) Not known
19. The level of the Aral Sea has been increasing.
A) True B) False C) Not known
20. Soon the traditional printed road maps may be out of use. 
A) True B) False C) Not known

скласти твір француською мовою на тему моя олюблена погода. дуже дякую.

Приведите пример линейной функции , график которой параллелен функции,  выраженной уравнением  у =-3x +1, графику