Solution:

The first door.

The bear will try to protect the cub, even if you offer her your food.
Swimming a lake with crocodiles is definitely not a good idea.
You can use your bucket to fight the fire with the water from the lake and can also distract the crocodiles with the food you had.

Solution:

Chicken-8

Explanation:
Let's start with distinct features

Chicken-2 has an extra toe.
Chicken-3 has fewer tail feathers.
Chicken-5 has only one thigh crease.
Chicken-6 has an extra feather around the neck.
Chicken-7 is looking up.
Chicken-8 has a longer butt crease.

But this riddle is not about the features. The different chicken is 8 as cannot be seen by any chicken.

Solution:

19.

The numbers are marked in the picture below,

Solution:

The person driving the car is the safest person.
(I loved this trick teaser)

Solution:

8.

Explanation:
- The Wire of the extension cord-1 is broken.
- The extension cord-6 does not have a wire.
- One of the sockets of cord-2 is broken
- The cord-4 with just one socket is of no use.

Now,
- Cord-1 will connect to the main switch and one of the sockets will connect to Cord-2.
So two sockets can be used from cord-1.

- One of the sockets of cord-2 will connect to the cord-5 and one of them is useless.
So two sockets can be used from cord-2.

- Cord-5 can use all the sockets, i.e. 4

So,
Total In Use = 2 + 2 + 4 = 8.

Please watch the video for a better understanding

Solution:

Tank F.

For an explanation, please visit the video.

Solution:

1

Explanation.
At every step number of joints goes down by 1.
i.e
8 have 6 joints
9 have 5 joints
5 have 4 joints
3 have 3 joints
7 have 2 joints
1 has 1 joint

You can also watch the video for an explanation

Solution:

The Patient will follow the path from room number-13 to room-no.4 as shown in the picture below.

Solution:

1 7
X 4
---
68
25
---
93

For an explanation, you can watch the video.

Solution:

Add two squares as shown in the picture below.