Answer:
The presence of the contaminant increases the total mass.
And on continuous heating to remove the volatile impurities, the hydrated salt gets overheated and the anhydrous salt gets thermally decomposed thereby producing a gas.
The heating leads to the formation or release of a gas which leads to loss of a higher percentage of mass from the compound making the mass percent of water in the hydrated salt too high and the mass of the anhydrous salt remaining in the crucible too low.
Hydrated Salt ⇒ Anhydrous salt + Water hydration

Answer:
Aluminum oxide
Explanation:
Just answered and was right
lowest melting point-covalent solids
highest melting point-ionic solids
Answer:
B
Explanation:
Firstly, we will need to calculate the number of moles. To do this, we make use of the ideal gas equation
PV = nRT
n = PV/RT
The parameters have the following values according to the question:
P = 780mmHg, we convert this to pascal.
760mHG = 101325pa
780mmHg = xpa
x = (780 * 101325)/760 = 103,991 Pa
V= 400ml = 0.4L
T = 135C = 135 + 273.15 = 408.15K
n = ?
R = 8314.463LPa/K.mol
Substituting these values into the equation yields the following:
n = (103991 * 0.4)/(8314.463 * 408.15)
= 0.012 moles
Now we know 1 mole contains 6.02 * 10^23 molecules, hence, 0.012moles will contain = 0.012 * 6.02 * 10^23 = 7.38 * 10^21 molecules
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