It is deaf, Dumb and Blind!!!

Still, always tells the truth. What is it?

Two in a corner, one in a room, zero in a house, but one in a shelter. What am I?

Can you find out the smallest number that can be conveyed as the sum of three squares in three unique ways?

Can you decipher these quotes by Albert Einstein?
Blf xzm mvevi hloev z kilyovn lm gsv ovevo lm dsrxs rg dzh xivzgvw.

There were two grandmothers and their two granddaughters.
There were two husbands and their two wives.
There were two fathers and their two daughters.
There were two mothers and their two sons.
There were two maidens and their two mothers.
There were two sisters and their two brothers.
Yet there are only six, who are buried here,
All are born legitimate and relationships clear.
How can this happen?

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

John was running from 40 thieves. John has got 3 gold boxes which weigh as 4kg, 2kg, and 1kg respectively. A witty man asked John to stay with him for seven days in exchange for 1kg gold per day. John needs to stay there for seven days and also do not want to give the witty man any advance. How can John pay for his seven days stay?

A pond had 60 fish, out of which, all but 20 died.
How many fishes are now present in that pond?

In my garden, I have many trees but only one of them is the mango tree. In these mango trees, there are some mangoes(as expected).

But after a strong wind, there are neither mangoes on the tree nor on the ground. Explain?

I am soft and cuddly that soothe your heart. But, If you pick my last name I am going to tear you all apart. Who am I?