Solution:

One of 57620 or 57628 must be the secret code.

Explanation:
Hint-1: 79314
Only 7 is there and in wrong

Hint-2: 95643
6 is in the right position while 5 is not

Hint-3: 57319
5 and 7 are in the right position

Sum Hint: A + B + C + D + E = D*10 + E
CaseA - 57620
5 + 7 + 6 + 2 + 0 = 2 * 10 + 0
20 = 20

CaseB - 57628
5 + 7 + 6 + 2 + 8 = 2 * 10 + 8
28 = 28

Solution:

Costa

Explanation:
c + 1 characters-> d
o + 2 characters-> q
s + 3 characters-> v
t + 4 characters-> x
a + 5 characters-> f

=> dqvxf = costa

Solution:

The ball will take infinite bounces before it is stopped. As per the question it will keep on bouncing half way up every time it hits the ground. But gravity will play its part at certain point of time which will make it stop.

Solution:

Since every bacterium divides into two in two minutes and we know the fact that the dish was half filled with bacteria at 3 pm, after exactly 2 minutes, all will divide into two and will fill the petri dish. Thus, the petri dish will become full at 3:02 pm.

Solution:

Kid1, he was left with one rock.

Solution:

I filled a glass full of water and held it over my head for 20 minutes.

Solution:

The guard and the prisoner cross the river
The guard comes back
The guard and the girl cross the river.
The guard and the prisoner comes back.
The mother and the girl cross the river.
Mother comes back
The mother and the father cross the river
Father comes back
The guard and the prisoner cross the river
Mother comes back
The father and the mother cross the river
Father comes back
The father and the boy cross the river
The guard and the prisoner comes back
The guard and the boy cross the river
The guard comes back
The guard and the prisoner cross the river.

Solution:

Are you Thorgan

Explanation:
Below will be the reply of three brothers:
Eden: No (speaks truth)
Thorgan: No (speaks lie)
Kylian: Yes (speaks lie)

Therefore if its Kylian then only you will get a reply as "Yes" and then you ask for your money.

Solution:

Solution can be verified from the picture below.

Solution:

Can be found on the pic below.

Solution:

The two numbers are 4 and 13 whose product is 52 and sum is 17.