Fluorine
Explanation:
F- has the lowest ionisation energy
I can't answer the question without the statements but I can tell you Calorimetry means measuring amounts of heat released or received during a chemical reaction.
Answer: The empirical formula is 
Explanation:
Mass of Pb = 4.33 g
Mass of O = (5.00-4.33) g = 0.67 g
Step 1 : convert given masses into moles
Moles of Pb =
Moles of O =
Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.
For Pb = 
For O = 
The ratio of Pb O= 1: 2
Hence the empirical formula is 
Explanation:
I think at HF is the answer because the pH value of weak acid are 4 and 5
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