Answer:
9 (1-2x²)
Explanation:
The given expression is:
30 - 9x²*2 - 21 - 4 + 4
The first step is to compute the multiplication. This will give:
30 - 18x² - 21 - 4 + 4
Then, we will add like terms as follows:
(30-21-4+4) - 18x²
= 9 - 18x²
Finally, we can take the 9 as a common factor from both terms, this will give:
9 (1-2x²)
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Answer:
Explanation:
Taking into account the definition of Avogadro's Number, the correct answers are:
1 mole of any element contains 6.023×10²³ atoms
1 mole of any compound contains 6.023×10²³ molecules
You have to know that Avogadro's Number or Avogadro's Constant is called the number of particles that make up a substance (usually atoms or molecules) and that can be found in the amount of one mole of said substance. Its value is 6.023×10²³ particles per mole.
Avogadro's number represents a quantity without an associated physical dimension, so it is considered a pure number that allows describing a physical characteristic without an explicit dimension or unit of expression.
Avogadro's number applies to any substance, because the number of elementary units in a mole of a substance is, by definition, a constant that does not depend on the material or the type of particle considered.
So, in this case, the correct answers are:
1 mole of any element contains 6.023×10²³ atoms
1 mole of any compound contains 6.023×10²³ molecules
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In stars helium atoms are used with hydrogen atoms in order to produce energy.
Answer: A )
