Full workings for Hard Riddles Set 1, including a step-by-step for the painting riddle, which is far easier to follow written down than said aloud.
What can you break without ever touching it?
Answer: a promise
A promise is broken by not honouring it, never by physical force.
I am taken from a mine and shut inside a wooden case, from which I am never released, and yet almost everyone uses me. What am I?
Answer: pencil lead
Graphite is mined, sealed inside a wooden pencil, and used without ever leaving the case.
What word becomes shorter when you add two letters to it?
Answer: short
Add 'er' to the word 'short' and you get 'shorter'.
A man looks at a painting and says: Brothers and sisters I have none, but that man's father is my father's son. Who is in the painting?
Answer: his son
With no siblings, 'my father's son' can only be the speaker himself. So the man in the painting has the speaker as his father, which makes him the speaker's son.
What occurs once in a minute, twice in a moment, and never in a thousand years?
Answer: m
The letter M appears once in 'minute', twice in 'moment', and not at all in 'a thousand years'.
I am an odd number. Take away one letter and I become even. What am I?
Answer: seven
Take the S off 'seven' and you are left with 'even'.