Answer: a)Copper and tin
Explanation: Copper and tin came into use at very early ages in the form of utensils, ornament etc. They were discovered in a way that it is possible for the people of early ages to extract these metals and melt them to give it some kind of shapes and utilize it for their daily living.People also started using these metals in the form of alloys as well which expanded the used of metals like copper, tin , bronze etc. Thus, correct option is copper and tin.
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.
Answer:
B
Explanation:
Natural Resource is a source of energy that doesn't need any action from humans. The sun doesn't need the help of humans, therefore it is a natural resource
Sardinia
The Tyrrhenian sea is apportion of the Meditter Sea and seperates Sardinia from Italy.