Solution:

Tank-5

Explanation:
This is a variation of Which Tank Will Fill First Brain Teaser but in this puzzle connection between tank-5 and tank-2 is closed so water will go into tank-5 from tank-1 but not go to tank-2. Therefore tank-5 will be filled first.

Solution:

The Stars

Solution:

A) Yes

Explanation"
There are two scenarios.

Scenario-1: Millie is married
Millie is looking at Stones(not married)

Scenario-2: Millie is not married
Terry(married) is looking at Millie

Solution:

Eye

Explanation :
It is written with two letters. ( 'E' and 'y')
It is said with the one. ( I )
It usually is seen with the two. ( two eyes)

Solution:

Costa

Explanation:
c + 1 characters-> d
o + 2 characters-> q
s + 3 characters-> v
t + 4 characters-> x
a + 5 characters-> f

=> dqvxf = costa

Solution:

In a clock.

Explanation:
time is 12 hour 10 minutes (here by looking at 2, we say 10 minutes)

Solution:

The frost when it's switched off.

Solution:

Just 4.

Explanation:
She blew four candles, therefore remaining six candles will burn out.

Solution:

It's shown in the picture below.

Solution:

16

Explanation:
9 [1x1] squares
5 [2x2] squares
1 [4x4] square
1 [4x4] square

9 + 5 + 1 + 1 = 16 squares.