What has 13 hearts but no other organs?

I know a nine-letter word having only one vowel.
Do you ?

How can you make the following equation true by drawing only one straight line: 5+5+5=550 ?

There is a square of a particular number which when doubled, becomes 7 more than its quarter.

Can you find the number?

What has many keys but can’t open a single lock?

You have two jars of chocolates labelled as P and Q. If you move one chocolate from P to Q, the number of chocolates on B will become twice the number of chocolates in A. If you move one chocolate from Q to P, the number of chocolates in both the jars will become equal.

Can you find out how many chocolates are there in P and Q respectively?

What 8 letter word can have a letter taken away and it still makes a word. Take another letter away and it still makes a word. Keep on doing that until you have one letter left. What is the word?

Solve the rebus riddle in the picture below.

I want to fill my bucket using both cold and hot water.
I have two taps for both cold and hot water. The hot water tap fills the bucket in exact 6 hours and the cold water tap fills the bucket in exact 4 hours.
I turn both of them simultaneously but I forgot to turn off another tap which removes the water out of the bucket. This tap can empty the bucket in 12 hours.

How Long will it take to fill the bucket?

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