Buy me, smell me or deliver me, I do not change.

Who am I?

Two friends Smith and Andrew were talking about the bravery of their families. Smith told great stories about his courageous grandfather who fought for Britain in "World War I". Andrew told that his grandfather was so brave that in 1919 just after the war he was honoured with a bravery medal with the words "For our Courageous Soldiers In World War I" embedded into it. Smith knows that his friend is lying. How?

John is selling fruits.
He sells grapes at $30, Dates $25, and a Wolfberry $45.
At what price does he sell fig?

PS: Logical Thinking

I am a white box having no key or lid.
Yet there is a golden treasure inside it.

What Am I?

Can you find a pattern and the missing number in the series given below?

100, 155, 258,? , 584, 819.

John and Jacob are twin brothers. One of them is a liar whereas the other one is a truth-teller.

I called their home number and one of them picked up.
I asked. 'Does John lie?' The person replied with a yes.

Whom did I talk with, John or Jacob?

I have branches, but no fruit, trunk or leaves. What am I?

13 decks of cards have been mixed. What is the minimum number of cards that must be taken out from the above-mixed cards to guarantee at least one 'four of a kind?

What mathematical symbol can be put between 5 and 9, to get a number bigger than 5 and smaller than 9?

When it's bad luck to meet a black cat?