<span>Based on the experience of the responder, to correctly calculate measurements in real-world. Firstly is to avoid errors as much as possible. Errors are what makes your measurement invalid and unreliable. There are two types of error which is called the systematic error and the random error. Each error has different sources. Words that were mentioned –invalid and unreliable are very important key aspects to determine that your measure is truly accurate and consistent. Some would recommend using the mean method, doing three trials in measuring and getting their mean, in response to this problem.</span>
i dont think their are a exact number
Answer : The mass in grams of calcium sulfate is 0.16 grams.
Explanation :
Molarity : It is defined as the number of moles of solute present in one litre of solution.
Formula used :

Solute is, 
Given:
Molarity of
= 0.0025 mol/L
Molar mass of
= 136 g/mole
Volume of solution = 485 mL
Now put all the given values in the above formula, we get:


Thus, the mass in grams of calcium sulfate is 0.16 grams.
Phase 3 is the integration phrase
Answer: C.) SO2
Explanation: Sulfur Dioxide is the gaseous molecule which can show the resonance through lewis dot structure due to the presence of lone pairs of electrons present on all of the three atoms of the molecules. Moreover , Sulphur forms pie bond with the oxygen using p orbitals which forms a network of the conjugated system that help to elaborate the reason of the formation of the resonance structure.
Options (a), (b), and (d) cannot form resonating structures as they involve the formation of the chemical bonds through single sigma bond.