Find the Next Number in the Sequence

2 9 3 1 8 4 3 6 5 7 ?

What is a word made up of 4 letters, yet is also made up of 3. Sometimes is written with 9 letters, and then with 4. Rarely consists of 6, and never is written with 5.

In a competitive exam, each correct answer could win you 10 points and each wrong answer could lose you 5 points. You sat in the exam and answered all the 20 questions, which were given in the exam.
When you checked the result, you scored 125 marks on the test.

Can you calculate how many answers given by you were wrong?

I have feet, but no legs. Which animal Am I?

No matter how little or how much you use me, you change me every month. What am I?

Can you find the mistake in the below statement?

After undergoing a successful eye operation, A blind girl has just boarded a train to her home. The doctor asked her to open the bandages after 3 hours. On her train journey, she opened the bandages and within a fraction of the time she commits suicide by jumping off the train.

Though her operation was successful, Why did she commit suicide?

Remove two matchsticks to make the below equation correct.

How many triangles are there in the picture below?

What has hands, but can’t clap?