This is hard to show but here is how you would determine these. NOTE each dot is an electron.
<span>Question 1) </span>
<span>F-H </span>
<span>1) determine the valance electrons for each. F has 7 and H has 1 </span>
<span>2) one electron from both F and H form the bond "-" which means that you still have 6 electrons to place around F and none to place around H. Place the 6 in sets of 2 around the F </span>
<span>.. </span>
<span>F-H </span>
<span>¨ </span>
<span>Question 2) </span>
<span>2) H-O-H </span>
<span>H has 1 valence electron minus 1 used in the bond to O = 0 electrons to place </span>
<span>H has 1 valence electron minus 1 used in the bond to O = 0 electrons to place </span>
<span>O has 6 valence electrons minus 2 used in the bonds to the H's = 4 electrons to place </span>
<span>H-O-H: place two dots above and below the oxygen </span>
<span>Question 3) </span>
<span>3) O=N----H : NOTE: a double bond requires O and N to share two of their electrons each </span>
<span>O has 6 valence electrons minus 2 used in the bonds to N = 4 electrons to place </span>
<span>N has 5 valence electrons minus 3 used in the bonds to O and H = 2 electrons to place </span>
<span>H has 1 valence electron minus 1 used in the bond to N = 0 electrons to place </span>
<span>place the 2 dots on top and bottom of oxygen. </span>
<span>place 2 above the N </span>
Hi there,
NH3 has the weight of 17.03 grams, and SF6 has the weight of 146.06 grams
so in total, there is 163.09 grams
Hope this helps :P
The amount left after 20 years = 154.15 mg
<h3>Further explanation
</h3>
The atomic nucleus can experience decay into 2 particles or more due to the instability of its atomic nucleus.
Usually radioactive elements have an unstable atomic nucleus.
The main particles are emitted by radioactive elements so that they generally decay are alpha (α), beta (β) and gamma (γ) particles
The decay formula for isotope :

Then for t=20 years, the amount left :

Answer:
0.500 mol/dm³
Explanation:
Using the formula below;
CaVa = CbVb
Where;
Ca = concentration of acid (mol/dm³)
Cb = concentration of base (mol/dm³)
Va = volume of acid (cm³)
Vb = volume of base (cm³)
In accordance to the information provided in this question is;
Va = 5cm³
Vb = 250 cm³
Ca = 12 mol/dm³
Cb = ?
Using CaVa = CbVb
12 × 5 = Cb × 250
60 = 120Cb
Cb = 60/120
Cb = 0.500 mol/dm³
They have high melting and boiling points and are hard and brittle