I believe it is d hope this helps :)
<span>Nitrogen trifluoride - NF3.
1 mol NF3 contains 1 mol atoms of Nitrogen
2.49 mol NF3 contains 2.49 mol atoms of Nitrogen
1 mol ---- 6.02 *10²³ atoms
2.49 mol ----- 2.49*6.02*10²³ = 15.0*10²³ atoms of N</span>
Answer is: <span>solid wood.
There are </span>five fundamental states of matter (gas, liquid, solid, plasma and Bose–Einstein condensate).
<span>In solid, molecules are closely packed, stiff and do not changes of shape or volume. S</span><span>olid object (in this example wood) does not take on the shape of its container.
</span>Liquids (in this example water) <span>have definite volume, but no fixed shape.
</span>Gases (in this example nitrogen and neeon) not have definite volume and fixed shape, it depends on its container.
Answer:
See the figure
Explanation:
In this case, we have to take into account the <u>stability of the carbocations</u>:
Terciary>Secundary>>Primary.
In other words, is we have the <u>most substituted carbocation</u> we will have more stability. Therefore in the carbocation formation, the charge would go in the <u>most substituted carbon</u> of the double bond for each case.
The correct statement : The atomic number of the radioactive nuclide is 90.
<h3>Further explanation</h3>
In the following element notation,

X = symbol of elemental atom
A = mass number
= number of protons + number of neutrons
Z = atomic number
= number of protons = number of electrons, on neutral elements
The symbol for a radioactive nuclide :

atomic number = 90
mass number = 234
number of neutrons = 234-90=144
number of protons = atomic number = 90