Answer:
The percent by mass of 3.55 g NaCl dissolved in 88 g water is 3.88%
Explanation:
When a solute dissolves in a solvent, the mass of the resulting solution is a sum of the mass of the solute and the solvent.
A percentage is a way of expressing a quantity as a fraction of 100. In this case, the percentage by mass of a solution is the number of grams of solute per 100 grams of solution and can be represented mathematically as:

In this way it allows to precisely establish the concentration of solutions and express them in terms of percentages.
In this case:
- mass of solute: 3.55 g
- mass of solution: 3.55 g + 88 g= 91.55 g
Replacing:

Percent by mass= 3.88%
<u><em>The percent by mass of 3.55 g NaCl dissolved in 88 g water is 3.88%</em></u>
Missing question: Z:X = 7:1 A:Z = 2.5:1 A:Z = 2.2:1 Y:X = 11:1.
Answer is:<span> Z:X = 7:1 and Y:X = 11:1.
Law of multiple proportions or Dalton's Law
said that the ratios of the masses of the second element which
combine with a fixed mass of the first element will be ratios of small whole
numbers.
In this example ratios are whole numbers, A:Z = 2.5 : 1
and A:Z = 2.2 : 1 are not whole number ratios.</span>
Molarity= mol/ liters
since the molarity is given, we can assume that we have 1.0 Liters of solution
15.6 M= mol/ 1 liters---> this means that we have 15.6 moles of HNO3
we need to convert these moles to grams using the molar mass of HNO3
molar mass HNO3= 1.01 + 14.0 + (3 X 16.0)= 63.01 g/mol
15.6 mol HNO3 (63.01 g/ mol)= 983 grams HNO3
now we have to determine the grams of solution using the assumption of 1 liters of solution and the density
1 liters= 1000 mL
1000 mL (1.41 g/ ml)= 1410 grams solution
mass percent= mass of solute/ mass of solution x 100
mass percent= 63.01/ 1410 x 100= 4.47 %
Well physical would be if you have Clay and you molded into a new shape or if you put butter on your toes and it melts or water evaporating from the surface of the ocean chemical changes would be milk going sour jewellery tarnishing which means turning into a different color or rust bread putting it in the oven and turning it into toes or rust forming on the nail that is left outside