Chemistry: Acids and Bases multiple choice help?

I need some help with my homework because my teacher left for vacation early and the sub doesn't know anything :P

a conjugate acid is an acid that forms when

a. the acid gains a proton

b. a base loses a proton

c. a base gains a proton

d. both (a) and (b)

an amphoteric species will accept a proton in the presence of a

a. strong acid

b. strong base

c. both (a) and (b)

d. none of the above

what is the [H3O+] in a of a .0040 M solution of NaOH. (not a typo on my part, that's literally what it says on my paper)

a. 2.5 x 10^-11 M

b. 4.0 x 10^-11 M

c. 2.5 x 10^-10 M

d. 4.0 x 10^-10 M

if the pH of a solution is increased from 2.0 to 4.0, the [H3O+] concentration

a. decreases by a factor of 2

b. decreases by a factor of 100

c. increases by a factor of 3

d. increases by a factor of 1000

a strip of universal pH paper

a. is a convenient measure of pH

b. is a precise measure of pH

c. must be calibrated with a pH meter

d. shows very little color change over a wide pH range

a pH meter measures the pH of a solution by measuring the

a. amount of charge on the hydronium ion

b. color of a solution

c. concentration of a solution

d. voltage difference between two electrodes in the meter's probe

thank you very much for your help. fyi, this is from a set of 20 question, the rest of which i managed to solve. these sort of tripped me up and im seeking some confirmation. so no bs about me not doing my homework :P