What's the best place to go shopping in the ocean?

This puzzle is for Harry Potter fans. Do you know why Tom Riddle is called Lord Voldemort?

Pronounced as one letter,
And written with three,
Two letters there are,
And two only in me.
I am double, I am single,
I am black blue and grey,
I am read from both ends,
And the same either way.

If,

A + B = C
D - C = A
E - B = C

Based on the above equations, find out the answer for:

D + F = ?

Can you divide numbers from 1 to 9 (1 2 3 4 5 6 7 8 9) into two groups so that the sum of the numbers of each group is equal?

Note: 9 cannot be turned over to make it 6.

John was born on March 5, 1970, in Delhi, India. Jacob was born 25 days before John. The year when they took birth, Republic Day fell on Monday.

Can you find out on what day was Jacob born?

Take one out and scratch my head, I am now black but once was red. What am I?

What type of tree can I carry in my hand?

What is the largest amount of money that you can possess in change and still if someone asks you for a dollar, you won't be able to give?

Replace the question mark with the correct number in the below-given picture?