chemistry problems i need help with?

Question

1. How many grams of KCl are in 10ml. of a .10M solution

a) 1.0 * 10 to the -3g
b) 0.013g
c) 0.075g
d) 1.0g
e) 75g

how is this solved

2. Which of the following substances would conduct electricity best when in liquid form

a) C6H12O6
b) H2O
c) KF
d)H2S
e) CO2

3. Which of the following compounds contains a polyatomic ion

A) KBr
b) Na2So4
c) C6H12O6
d)CO2
e) LiCL

Answer 1

a) mass of KCl =39+35.5 =74.5g
1l of KCl0.1m =7.5*.-0.1=7.45g/l = 7.45*10^-3g /ml
and in 10ml 7.45*10^-2=0.0745 answer c is correct

b) KF salt of a strong acid HF and strong base KOH, good electrolyte

c)B) Na2 SO4 SO4-- is a polyatomic ion