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asambeis [7]
3 years ago
6

Which statements describe the elements? Which ones are true and which ones are false?

Chemistry
1 answer:
Alchen [17]3 years ago
8 0

Answer:

Explanation:

Uma declaração verdade é identificada pelo de ela afirmar a verdade diferente das outras opções

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Help ill give brainliest need help with number 8
kotegsom [21]

Answer:

the sun goes away and takes heat with it

Explanation:

5 0
3 years ago
Read 2 more answers
Write a nuclear equation to describe the neutron induced fission of Pu-239 to form Kr-89 and Ce-149 (this fission is induced by
zlopas [31]

Answer:

\rm 2_{0}^{1}\text{n} + \, _{94}^{239}\text{Pu} \longrightarrow_{36}^{89}\text{Kr} + \, _{58}^{149}\text{Ce} + \, 3_{0}^{1}\text{n}; three

Explanation:

If the fission is induced by two neutrons, the unbalanced equation is

2\rm _{0}^{1}\text{n} + \, _{94}^{239}\text{Pu} \longrightarrow_{36}^{89}\text{Kr} + \, _{58}^{149}\text{Ce} + \, x_{0}^{1}\text{n}

The main point to remember in balancing nuclear equations is that the sums of the superscripts and the subscripts must be the same on each side of the equation .  

Balancing the superscripts, we get

2 + 239 = 89 + 149 + x

      241 = 238 + x

          x = 3

The balanced nuclear equation is

\rm 2_{0}^{1}\text{n} + \, _{94}^{239}\text{Pu} \longrightarrow_{36}^{89}\text{Kr} + \, _{58}^{149}\text{Ce} + \, \mathbf{3}_{0}^{1}\text{n}

\text{The fission produces } \boxed{\textbf{three}} \text{ neutrons}

4 0
3 years ago
An experiment applies heat to a substance and produces a gas that is a new and different substance. Choose the true statement.
sergejj [24]
Im a bit torn here, lets look at the definitions of physical and chemical changes:
physical change changes only the phase/state of a substance, but not what the substance is
chemical change is a chemical reaction where a new substance is formed and energy is given off or absorbed.
(it just started raining and it smells really nice out my window)

clearly, this cannot be just a physical reaction. i think i would be inclined to pick B. but C. could have merit as an answer too. sorry for the ambiguity x
7 0
3 years ago
What is the mass of 1 mole of carbon?
Sergio [31]
Your answer is B. 6.02 x 1023 grams

6 0
3 years ago
Which statement best describes the properties of covalent compounds?
AnnyKZ [126]
Covalent network. <span>A solid that is extremely hard, that has a very high melting point, and that will not conduct electricity either as a solid or when molten is held together by a continuous three-dimensional network of covalent bonds. Examples include diamond, quartz (SiO </span><span>2 </span>), and silicon carbide (SiC). The electrons are constrained in pairs to a region on a line between the centers of pairs of atoms.<span>


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4 0
3 years ago
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