Why Aeroplane windows are round?

There is a hypothetical state between the USA and Mexico border 'Tango'.
Here 70 percent of the population have defective eyesight, 75 percent are hard of hearing, 80 percent have Nose trouble and 85 percent suffer from allergies, what percentage (at a minimum) suffer from all four ailments?

What comes
Once in a Year
Twice in a Month
4 times in a Week
6 times in a Day

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

What you cannot hold but it is yours?

Only one colour, but not one size,
Stuck at the bottom, yet easily flies.
Present in sun, but not in rain,
Doing no harm, and feeling no pain.
What is it?

There's a day, that comes around once a year.
To celebrate the man, you hold dear.
He gave you life, love and will pick you up if you fall.
When it comes to guys like him, He's the best of all.
Who is he?

Can you solve the below algebraic mathematical equation?

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

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?