1- Calculate the percent by mass of potassium... 295 mL of water. Density of water is 0.997 g/mL

1- Calculate the percent by mass of potassium nitrate in a solution made from 45.0 g KNO₃ and
295 mL of water. Density of water is 0.997 g/mL
A. 1.51%
B. 7.57%
C. 13.3%
D. 15.2%
E. none of them
2- How many grams of water are needed to dissolve 27.8 g of ammonium nitrate NH₄NO₃ in order
to prepare a 0.452 m solution ?
A. 0.157 g
B. 36.2 g
C. 100 g
D. 769 g
E. 157 g
3- In how many grams of water should 25.31 g of potassium nitrate (KNO₃) be dissolved to
prepare a 0.1982 m solution ?
A. 250.0 g
B.792 g
C.1000 g
D. 1263 g
E. 7917 g
4- The solubility of gases in water usually decreases with :
A. increased pressure .
B. increased temperature .
C. decreased temperature .
5- The solubility of nitrogen gas at 25°C and 522 mm Hg is 4.7x10¯⁴ mol/L .What is the value of
Henry’s Law constant in mol/L atm ?
A. 6.8 x 10¯⁴ mol/L atm
B. 4.7 x 10¯⁴ mol/L atm
C. 3.2 x 10¯⁴ mol/L atm
D. 9.0 x 10¯⁷ mol/L atm
E. 1.5 x 10³ mol/L atm
6- The solubility of CO₂ gas in water :
A. increases with increasing temperature .
B. decreases with decreasing temperature .
C. decreases with increasing temperature .
D. is not dependent on temperature .
12.24 According to Raoult’s law , which statement is false ?
A. the vapor pressure of a solvent over a solution decreases as its mole fraction increases .
B. the solubility of a gas increases as the temperature decreases .
C. the vapor pressure of a solvent over a solution is less than that of pure solvent .
D. the greater the pressure of a gas over a solution the greater its solubility .
E. ionic solutes dissociate in solution causing an enhancement of all colligative properties .
12.27 Dissolving a solute such as KOH in a solvent such as water results in :
A. an increase in the melting point of the liquid .
B. an decrease in the boiling point of the liquid .
C. an decrease in the vapor pressure of the liquid .
D. no change in the boiling point of the liquid .
12.29 Which of the following aqueous solution has the highest boiling point ?
Given K=0.52°C/m.
A. 0.2m KCI
B. 0.2 m Na₂SO₄
C. 0.2 m Ca(NO₃)₂
D. pure water .
E. more than one of the above .