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

You see me once in June, twice in November, and not at all in May. What am I?

You are playing as white and given four rooks to checkmate the black king in four moves with the following rules 1. You can place one rook every move and ensure the black king should be in check position.2. After four moves the black king should be in the checkmate position.

Can you solve the below tricky visual equation?

You need to complete the maze by entering from the entrance marked below in the figure near the yellow circle, bottom left and leaving from the exit point near the green circle, bottom middle.

Rule of Game: You can move only by exchanging green and yellow circles.

John went to a parrot shop in Mexico, and the parrot owner told him that his parrot is so unique that he repeats everything he hears. John got excited and immediately bought the parrot. John went home and spoke many words, but the parrot does not repeat anything.
He went again to the parrot shop and complaint to the shopkeeper, but the shopkeeper never lied. Explain?

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?

Can you solve the below algebraic mathematical equation?

(J+O+I+N+T)3 = JOINT

How can you write nineteen in a manner that if we take out one, it becomes twenty?

Before Mount Everest was discovered, what was the highest mountain in the world?