Can anyone tell me a word in the English dictionary which has a silent 'z'?

My cousin lives in one story house in Antarctica. His house is made the of-of sandstone. what is the color of stairs?

The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

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?

Identify Me

Hint1: I am a god
Hint 2: I am a planet
Hint 3: measurer of heat

You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?

Name one eight-letter word with 'kst' in the middle, 'in' the beginning, 'and' at the end.?

Which point will the car reach to go out?

What does the below rebus riddle means?