Answer 1

float and double can hold floating point number which is something like this 5.555...
float and double are the same but double can hold bigger value than float.
long double can hold bigger value than double but it's up to the compiler.

long is just basic integer but can hold 2 times more bytes than int variable.

long = 4 bytes = 32bits
float = 4 bytes = 7 digits
long double = 8 bytes = 15 digits