Answer:
Volcanoes cool off the earth by emitting heat from its interior. They also add islands and for example, Hawaii was created / is made out of volcanoes. The deposits from volcanoes can also be used for building materials. Volcanic explosions have caused the atmosphere and oceans to form. Volcanic deposits also create land which is fertile.
Add proton + neutrons = Mass 37
Proton is same as your atomic mass= 17
If you go on the periodic table look up 17 and it will give u the letter.
Answer:
Explanation:
Pb(NO3)2(aq) + 2NaCl(aq) ==> PbCl2(s) + 2NaNO3(aq)
NO3- mixes with everything at beginning levels.
PbCl2 doesn't mix at all in water. It becomes a ppte, which means it is solid form. Your teacher might prefer using PbCl2(ppte). I think I'd ask to make sure.
The given question is incomplete. The complete question is :
Which of the following Group 17 elements is the least reactive
a) Flourine
b) Chlorine
c) Astatine
d) Iodine
Answer: c) Astatine
Explanation:
Halogen is the name given to Group 17 family with general electronic configuration of 
which have 7 valence electrons and thus easily gain one electron to attain stable configuration.
As we move down the group from flourine to chlorine to bromine to iodine to astatine , the valence shell moves farther from nucleus and thus tendency to accept the electron decreases and thus reactivity also decreases.
Thus Astatine is the least reactive of all.
