Answer:
When excess of carbon dioxide is passed in lime water, calcium carbonate is converted to calcium bicarbonate which is soluble, hence the milkiness due to calcium carbonate disappears.
Explanation:
Ca(OH)2+CO2 → CaCO3 (Milkiness) ↓+H2O
CaCO3+H2O+CO2 → Ca(HCO3)2 (soluble)
Given equation:
P + O2 → P2O5
In order for the equation to be balanced, the stoichiometry of the atoms of one kind on the reactant side must be equal to that on the product
Reactants Products
P = 1 P = 2
O = 2 O = 5
The balanced equation would be:
4P + 5O2 → 2P2O5
Reactants Products
P = 4 P = 4
O = 10 O = 10
Ans: D)
Start by converting mg to g. There is .001g in every miligram, so there is 0.4g in this sample.
Then find the molar mass of ibuprofen (C13H18O2) which is 206.3g/mol
Then divide grams by the molar mass to get moles of C13H18O2: (0.4g)/(206.3g/mol) = 1.94x10^-3mol C13H18O2
Then multiply moles by Avogadro's number to get molecules: (1.94x10^-3mol)/(6.02x10^23) = 1.17x10^21 molecules of ibuprofen (C13H18O2)
