The answer to A is hydrogen I think
Answer:
the 4th one is the corrent one
Answer:
Only to elements are gases at room temperature and standard pressure.
Fluorine and chlorine.
Explanation:
The group 17 is called halogen.
There are five elements in halogen group.
All halogens required one electrons to complete the octet and to get the noble gas electronic configuration.
All halogen elements have seven valance electrons.
Halogen elements:
Fluorine, chlorine, Bromine, iodine and astatine
Fluorine is gas at room temperature which s 25°C and standard pressure which is 1 atm.
It is present in the from of F₂.
Chlorine is also gas at room temperature and standard pressure.
It is present in the from of Cl₂.
The bromine is liquid under these condition.
Iodine and astatine are solids.
As we move down the group their melting and boiling points increases.
Answer:
6.02*10^23
Explanation:
This is the number for one mole. Just like one dozen = 12, one mole = 6.02*10^23.
Fun fact, if you had a mole of pennies you could spend 1 million dollars every second of your life and not have even spent 1% of it by the time you die at 100 years old.
