Atomic number (Z) of tungsten is 74
Mass number (A) of tungsten is 184
Now:
Atomic number of an element = Number of protons = Number of electrons
Mass number = Number of Protons + Number of neutrons
In the case of tungsten
Total Number of electrons = 74
Jeffrey has already added 21 electrons
Number of electrons needed = 74 - 21 = 53
Ans (D) 53 more electrons are needed to complete the neutral atom of tungsten.
<span>
Evaporation occurred between the reaction of the hydrochloric acid and the arsenic group because there is a formation of gas. A
liquid is cooled if condensation exceeds evaporation. This is because the cooling of the liquid decreases the kinetic energy of the
molecules. Their movement is being restricted by the colder temperature. The
molecules tend to be closer with each other. Also, because of their restricted
movement, the liquid may turn into solid due the colder temperature. An example
of this is the cooling of liquid water by placing it into the refrigerator into
solid water (ice).</span>
= 2 × 23 + 2 × 52 + 2 × 16
= 182 grams
1 mole of 
weighs = 182 g
8 moles weigh = 8× 182
=
or
Reactivity trends of halogen:
1) Melting point and boiling points increased down the
group
2) Colour becomes darker.
E.g. Fluorine (pale yellow)
Chlorine (yellowish-green)
Bromine (reddish-brown)
Iodine (purplish-black)
Astatine (black)
3) The reactivity decreases down the group.
Reactivity:
F > Cl > Br > I > At
0.953948 is what I got from dividing pressure value by 760.
