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

what one word does the below rebus identifies?

Teacher ask the student

'Why are you standing on that chair in music class ?'.

what did student replied ?

I look flat, but I am deep. Hidden realms I shelter. Lives I take, but the food I offer. At times I am beautiful. I can be calm, angry, and turbulent. I have no heart but offer pleasure as well as death. No man can own me, yet I encompass what all men must have. What am I?

Can you find the key in the picture below?

Can you count the number of triangles in the picture below?

If it took eight men ten hours to build a wall, how long would it take four men to build it?

A sundial has the fewest moving parts of any timepiece. Which has the most?

An infinite number of mathematicians are standing behind a bar. The first asks the barman for half a pint of beer, the second for a quarter pint, the third an eighth, and so on. How many pints of beer will the barman need to fulfill all mathematicians' wishes?

Place a mathematical symbol between the numerals 5 and 9 in such a way that the resulting number is greater than 5 but smaller than 9.