What is so fragile that saying its name breaks it?

A Doctor always sneezes before the rain. Doctor sneezes, Will it rain?

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

Identify Me

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

I have Rs.50 and I spend it in the way as below.

A worker is to perform work for you for seven straight days. In return for his work, you will pay him 1/7th of a bar of gold per day. The worker requires a daily payment of 1/7th of the bar of gold. What and where are the fewest number of cuts to the bar of gold that will allow you to pay him 1/7th each day?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

First, think of the colour of clouds. Next think the colour of snow. Last, think of the colour of the moon. Now, what do cows drink?

Once upon a time, there was a castle on a square island. The entire island was surrounded by a 14m wide trench. The Romans had wanted to invade the castle and had brought a few wooden planks along with them to facilitate themselves in crossing the moat. The planks were however found to be only 13m long.

The Romans still managed to cross the trench. How did they do it?

Can you complete the sequence?

192, 021, 222, 324, 252, 627, 2__, 9__?