1) is chemical Bonds
3) Conservation of mass
5) compound
hope i helped on the ones i could answer
As the question tells you, you need to use the formula
% mass= mass of solute/ mass of solution x 100
mass solute= 30.0 g
mass of solution= 30.0 + 270.0= 300.0 g
% mass= 30.0/ 300.0 x 100= 10%
answer is B
Answer:

Explanation:
Here in Calcium Chloride ionic bond is present in between calcium and chlorine atoms. As we know according to Octet rule calcium have two excess atoms and for matching nearest noble gas electronic configuration. It donate two electrons to gain more stability and form
, while chlorine is deficient from one electron to meet nearest noble gas electronic configuration therefore two chlorine atoms accept excess electron from calcium individually and form two
ions.

Hence aqueous solution of calcium chloride breaks the ionic bond pairing in one
and two
ions: 
Explanation:
Ok so water is H2O and cabon dioxide in the air is CO2, so the water goes through the carbon dioxide and makes acid rain H2SO4.
Now we have our limestone which is CaCO3.
What happens is that the acid breaks apart our limestone into Ca2+ and CO3 2-. This then reforms into Calcium bicarbonate Ca(CO3)2.
Calcium bicarbonate is soluble in water and is hence washed away by the rain eroding the limestone.