What has a head and a tail but no body?

What has 13 hearts but no other organs?

Which English word has three consecutive double letters?

What begins with an “e” and only contains one letter?

What’s a single-digit number with no value?

The more that there is of this, the less you see. What is it?

What’s always running but never gets hot?

What has branches, but no fruit, trunk, or leaves?