Scenario 1 is dependent. Each time you draw from the jar, the selection changes because you’re not replacing the previous marble. Scenario 2 is independent because the marbles are put back in the jar, so the odds do not chance.
In scenario 1, you have a 13/26 (50%) chance of selecting a blue marble. Now that you’ve removed that blue marble, there are now 13 red and 12 blue, so your chance of getting blue is 12/25 (48%). So your chance of getting two blue in a row is 13/26 x 12/25= .5 x .48= .24= 24%. Whereas in scenario 2, you have a 13/26 chance of getting a blue marble each time. So your chance of getting two blue in a row is 13/26 x 13/26= .5 x .5= .25= 25%. So you have a higher chance (by 1%) of getting two blue in a row in scenario 2 than 1
