Answer:
D. How frequently do earthquakes occur in San Francisco?
Answer:
It is an example of Exothermic reaction.
Explanation:
It leads to release of HEAT as can be seen water is given in gaseous form.
Answer:its the thrid one i think
Explanation:
Atoms in the same group (column) of the periodic table have similar properties. This is because all elements in the same group have the same amount of valence (outer) electrons.
So, any element directly above or below Calcium on the periodic table would have similar properties.
These would be Magnesium, Barium, Strontium, Radium, and Beryllium.
Okay, so the atomic mass of Cl2 is 35.5, so all you would have to do is multiply that by 2 to get 71.