I am filing out a study guide and needed coaching on some question. thank you

Question

0.765 g of He is placed in a balloon at 1.15 atm. The balloon expands to volume of 5.00 L. What is the temperature of the balloon?

a,3.45 K
b,91.6 K
c,93.4 K
d,366 K

Answer 1

At STP a sample of methane gas occupies a volume of 1250 mL. What is the volume of the methane at 100.°C and 760. torr?

a.1710 mL
b.1250 mL
c.915 mL
d.1420 mL

Answer 2

A solution is prepared by adding 25.0 g of methanol to water to make a total volume of solution of 95.4 mL. What is the weight/volume percent of this solution?

a.26.2%
b.3.81%
c.20.8%
d.25.0%

Answer 3

7.76 g of KBr was dissolved in water. The solution was diluted to a volume of exactly 250 mL. What is the molarity of the solution?

32.2 M

a.0.476 M
b.0.0652 M
c.0.0310 M
d.0.261 M

Answer 4

How many grams of Na2SO4 are present in 500. mL of a 0.750 M aqueous solution?

a.70.9 g
b.53.3 g
c.0.284 g
d.106 g
e.2.63 g

A serum concentration of Mg2+ of 1.75 mmol/L is equivalent to:

a.3.50 mEq/L
b.1.75 mEq/L
c.17.5 mEq/L
d.0.875 mEq/L

Answer 5

anyone know how to work out these problems?

Answer 6

i cant believe these arent answered yet. im sorry.
1. 366K
2. 1710 mL
3. 26.2
thats what i have so far