Answer:
it's Nitrogen. there is 78% of nitrogen in the atmosphere, 21% oxygen and others
Answer:
Lead
Explanation:
The economic success of United states was in no way imparted by the mineral lead.
In fact, the mineral is considered a toxic pollutant and has been banned. The United States like most countries are not interested in lead as a viable economic option.
It was once used in paints because they produce a highly durable mix.
Also, it was an additive in gasoline. This has been banned.
Answer and Explanation:
About two-thirds of the Earth's surface lies beneath the oceans. The depths of the open ocean were mostly a matter of speculation before the 19th century. Most people thought ocean floor was flat and featureless. In the early 16th century, a few navigators found that the open ocean can differ considerably in depth by taking soundings with hand lines, which shows that the ocean floor was not as flat as it believed.
At the beginning of the 1950s, scientists used magnetic instruments adapted from airborne devices to recognize odd magnetic variations across the ocean developed during World War II to detect submarines. They found that the iron-rich and volcanic rock make up the ocean floor-- contains a strongly magnetic mineral and can distort compass readings. In the early 18th century, this distortion was recognized by Icelandic mariners. Magnetite gives measurable magnetic properties; these magnetic variations help to study the deep ocean floor.
Mid ocean ridge
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