The last three questions are very important. Thank you!!

1. A standard sheet of paper is 8.5 x 11 inches. What is the surface area, in cm2, of one side of a sheet of paper? The answer should be 6.0 x 10^2 cm^2

2. How many miles are covered in a 15 km race? (1 mile = 5280 feet, 12 inches = 1 foot, 1 inch = 2.54 cm) Answer should be 9.3 miles

3. A solid with a mass of 19.3 g is added to a graduated cylinder filled with water to the 25.0 mL mark. After the solid sinks to the bottom, the water level is at 35.8 mL. What is the density of the solid? Answer: 1.79 g/mL

4. Silver (107.87 amu) has two naturally occurring isotopes. In a typical sample, 51.84% of silver exists as Ag-107 (106.9051 amu). Calculate the atomic mass of the other isotope. Answer: 108.91 amu

5. What is the total number of chlorine atoms present in 2.00 grams of magnesium chloride (MgCl2)? Answer 2.53 x 10^22 atoms

4. Silver (107.87 amu) has two naturally occurring isotopes. In a typical sample, 51.84% of silver exists as Ag-107 (106.9051 amu). Calculate the atomic mass of the other isotope. Answer: 108.91 amu

let the atomic mass of the other isotope is x
now  [51.84(106.9051) + (100-51.84)x]/100= 106.9051
solve it for x


5. What is the total number of chlorine atoms present in 2.00 grams of magnesium chloride (MgCl2)? Answer 2.53 x 10^22 atoms

Convert gm ----> moles of MgCl2 ----> moles of Cl ---> number of Cl atoms
2.00 g MgCl2 x 1mole MgCl2/ 95g of MgCl2  x 2moles of Cl/ 1mole of MgCl2  x 6.022 x 10^23 atoms of Cl/ 1 mole of Cl atoms

1. A standard sheet of paper is 8.5 x 11 inches. What is the surface area, in cm2, of one side of a sheet of paper? The answer should be 6.0 x 10^2 cm^2
Surface area = Length x breadth= 8.5 inches x 11 inches
Convert inches into cm and you will get the answer
1 inch = 2.54 cm
8.5 inches x 11 inches = 8.5 (2.5) x 11 (2.5)

2. How many miles are covered in a 15 km race? (1 mile = 5280 feet, 12 inches = 1 foot, 1 inch = 2.54 cm) Answer should be 9.3 miles
1 kilometer = 0.621371192 miles
so 15 km = 15 x 0.621371192 miles

3. A solid with a mass of 19.3 g is added to a graduated cylinder filled with water to the 25.0 mL mark. After the solid sinks to the bottom, the water level is at 35.8 mL. What is the density of the solid? Answer: 1.79 g/mL
density =mass / volume
  = 19.3 g/ 35.8mL