Out of four images which one is the odd one out?

By including only four matchsticks in below picture, you have to make "Four Triangles And Two Squares"

You board a train. The train will have to enter a tunnel soon. You are claustrophobic. Which place is the best for you to sit?

I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

Two fathers and two sons decided to go to a shop and buy some sweets upon reaching. Each of them bought 1 kg of sweet. All of them returned home after some time and found out that they had 3kg of sweets with them.

They did not eat the sweets in the way, nor threw or lose anything. Then, how can this be possible?

Imagine a box with two cogwheels, one big with 24 teeth and one small with 8 teeth. The big one is firmly attached to the center of the box which means it does not turn or move while the small one rotates around the big one.

How many times do you think that the smaller wheel will turn compared to the box when it turns once around the big one?

Do You See It?

Suppose that you are trapped on the surface of a frozen lake. The surface is so smooth and ideal that there is no friction at all. You cant make any grip on the ice and no wind is blowing to help you out. You have just a mobile phone with you which has got no reception disabling you to call for help.

How will you plan your escape before you freeze to death on the frozen lake?

How many Watermelons are there in the below picture?

Here is a mathematical expression that also secretly tells a movie name. What movie is that?