Answer:
0.109 g.
Explanation:
Equation of the reaction:
Na3PO4 + 3HCl --> 3NaCl + H3PO4
Number of moles of HCl = molar concentration × volume
= 0.1 × 0.04
= 0.004 mol.
By stoichiometry, 1 mole of Na3PO4 neutralises 3 moles of HCl. Therefore, number of moles of Na3PO4 = 0.004/3
= 0.0013 mol
Mass of Na3PO4 = molar mass × number of moles 
= 0.0013 × 164
= 0.219 g
Since 50% of Na3PO4 was present in the sample. Let 100 g be the total mass of the substance 
= 0.219 × 50 g/100 g
= 0.109 g.
 
        
             
        
        
        
Explanation:
Sulfur has 6 valence electron 
Valence electron shows group( in column)
 
        
             
        
        
        
melting point because the melting point is the heat required to make an object melt anything less than this poitn will not make the substence melt.
 
        
                    
             
        
        
        
Answer:
The answer is below
Explanation:
The separation technique is used for separating immiscible liquids. 
When separating, the stopper has to be removed when draining the lower layer so as to prevent a vacuum. If vacuum is allowed, the draining rate will reduce and stop.
The liquid should be mixed by shaking the funnel and then opening the stopcock so as the vent out gases.
When near interface between the layers, you should set your eye level so that you do not drain up to the second layer.
After completely draining the first layer, the second layer should be collected in a new flask.
After mixing the solutions in a separatory funnel, the stopper should be removed and the liquid should be mixed thoroughly and the layers allowed to separate. When you get close to the interface between the layers, get eye level with the funnel and slow the draining until the first layer is collected. Switch to a new flask to collect the second layer.