Aparticular element has the following set of properties:

it has a low melting point.
it has a low boiling point
it exists as a two-atom molecule in the gas phase.
it has seven outer electrons.
it readily reacts with metals to produce a salt.

which element does the list describe?
a. strontium (sr)
b. potassium (k)
c. krypton (kr)
d. bromine (br)

D. bromine (Br)

Explanation:

Bromine is an element of halogen group.

Halogens, or "salt-formers," are located in group 17 of the periodic table. The halogens have  the following properties:

1) They have low melting points and low boiling points.

2) They exist as diatomic molecules in the gas phase.

3) They have seven electrons in their outermost shell, which means they have seven valence

electrons.

4) They are highly reactive nonmetals.

5) They tend to gain electrons and form negative ions.

Thus the given properties are of Bromine.

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"

c.

explanation: