Can someone help? I will break down the problem...

Lab experiment that separates mixtures. I found mass of NH4CL=.19g, Salt= .86g, Sand= .86g

I don't know if I did this correctly but this is what I got:

FINDING NH4CL:

mass of evaporating dish: 39.96g

mass of evaporating dish and sample: 41.99g

total mass of sample: 2.09g

mass of evaporating dish and sample after heating: 41.80g

MASS of NH4CL= 0.19g

FINDING SALT:

mass of beaker and watch glass: 153.93g

mass of beaker, watch glass, and salt: 154.79g

MASS OF SALT: 0.86g

FINDING SAND:

mass of filter paper: 0.99g

mass of filter paper and dry sand: 1.85g

MASS OF SAND: 0.86g

TOTAL MASS RECOVERED: 1.91g

QUESTIONs- I answered these, could be wrong.

1. Percent ammonium chloride: 0.45%

2. Percent sodium chloride: 0.55%

3. Percent sand: 46.48%

4. Total: 47.48%

QUESTIONs:- I don't know these.

1. How did your recovered mass compare to the initial mass for this experiment?

2. What could have caused the mass to be higher than the initial mass?

3. What could have caused the mass to be lower than the initial mass?

4. Suggest a method of separating the following mixtures.

a) Iron filings and sulfur