Name a key which is hardest to turn.

What is the next number in this series?

4,12,84,3612....

What's the next in the series?

H, Be, F, S, Mn, Kr, In, Gd, Tl, ?

Can you spot the hidden girl in the picture below?

In the given picture, you can find two letters missing. When two particular letters are placed in the missing spots, you get an eight-letter word while reading in the anti-clockwise direction. Can you find out the missing letters and the missing word eventually?

An express train takes 3 seconds to enter the tunnel which is 1 km long.
If it is travelling at 120 km an hour, how long will it take to pass completely through the tunnel?

It has horns but can’t beep. It is like to bleat but It is not a sheep. What is it?

What is the word or phrase?

While house hunting in London, I came across a very good leasehold property Discussing the lease the landlady told me:

'The property was originally on a 99 years lease and two-thirds of the time passed is equal to four-fifths of the time to come. Now work it out for yourself and see how many years are to go!

Spot what is wrong here in below Picture?