Answer:
C. Y & Z
Explanation:
V, W are imaginary metals here because their valence electrons are typically less than 4. X, Y, Z are non-metals and have higher valence electrons. Here, if V or W bind with X, Y, or Z we make ionic bond (because metal + non metal = ionic). But, if X binds with Y or Z or any combinations of any two of the three non-metals results in covalent bond (non metal + non metal = covalent).
Thus, Y and Z make covalent.
True
Explanation:
Harry Hess in 1961 resurrected Wegener's continental drift hypothesis and also he mantle convection idea of Arthur Holmes by postulating the theory of sea floor spreading.
- After Wegener's postulation of the continental drift hypothesis, not much was done.
- It was only around 1931 that Arthur Holmes came up with the idea of a convecting mantle.
- After the second world war passed, new instruments were used to investigate and map the ocean floor.
- Through this, Arthur Holmes came up with the idea of a spreading sea floor.
- This gave a full gleam picture to the idea of a moving earth and the more accepted terminology of "Plate tectonics " came to the fore.
Learn more:
Sea floor spreading brainly.com/question/9912731
Continental drift brainly.com/question/5002949
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Considering mass percentages, stars in the vicinity of the sun contain only 2% other elements by mass. Other than the main components, hydrogen and helium, stars have some heavier elements such as carbon, nitrogen, oxygen and iron. These elements are found near or in the star's core and are ejected into space when the star dies.
