Answer:
34.15% is the mass percentage of calcium in the limestone.
Explanation:
Mass of precipitate that is calcium oxalate = 140.2 mg = 0.1402 g
1 mg = 0.001 g
Moles of calcium oxalate = 
1 mole of calcium oxalate have 1 mole of calcium atom.
Then 0.001095 moles of calcium oxalate will have 0.001095 moles of calcium atom.
Mass of 0.001095 moles of calcium :
0.001095 mol × 40 g/mol = 0.04381 g
Mass of sample of limestone = 128.3 mg = 0.1283 g
Percentage of calcium in limestone:

34.15% is the mass percentage of calcium in the limestone.
Answer: All solutions have two parts: the solute and the solvent. The solute is the substance that dissolves, and the solvent is the substance that dissolves the solute.
Hope that helps (:
Answer: im not writting a pharaphraph. Buuuuuuuuuuuut... explian the type of reaction then explanie how that type of reaction works.
Explanation:
Volume of Hydrogen V1 = 351mL
Temperature T1 = 20 = 20 + 273 = 293 K
Temperature T2 = 38 = 38 + 273 = 311 K
We have V1 x T2 = V2 x T1
So V2 = (V1 x T2) / T1 = (351 x 311) / 293 = 372.56
Volume at 38 C = 373 ml
1. carbon lies in the 2nd period where silicon in the third period.
2. carbon is a non metal whereas silicon is a metalloid.
3. there are only 3 isotopes of carbon and 23 isotopes of silicon
4. size of silicon atom is larger
5. silicon is heavier than carbon.