A number of possible explanations for why manhole covers are round include :

1. A round manhole cover cannot fall through its circular opening, whereas a square, rectangular, or oval manhole cover could fall in if it were inserted diagonally in the hole.

2. Circular covers don’t need to be rotated or precisely aligned when placing them on the opening.

3. A round manhole cover is easily moved and rolled.

4. Human beings have a roughly circular cross-section.

5. Round tubes are the strongest shape against the compression of the earth around them, so the cover of the tube would naturally be round as well.

6. It’s easier to dig a circular hole.

Given length of the rectangle = 3 cm

Breadth of the rectangle = 4 cm

Then, the diagonal of the rectangle D = 32 + 42 = 25 = 5

Then, it implies side of square = 5 cm

We know that Area of square = S x S = 5 x 5 = 25 sq.cm.

The common greenhouse gas containing only hydrogen and oxygen is H2O, this is water vapor.

The common greenhouse gases are water vapor, carbon dioxide, methane, nitrous oxide, and ozone.

The composition (chemical formula) of those gases are:

Water vapor: H2O
Carbon dioxide: CO2
Methane: CH4
Nitrous oxide: NO
Ozone: O3.

As you see the only one of those that contains only hydrogen and oxygen is H2O, water vapor.

CDs are the least risky investment choice when compared to flipping, renting and bonds.

A certificate of deposit (CD) is a savings certificate with a fixed maturity date, specified fixed interest rate and can be issued in any denomination aside from minimum investment requirements. A CD restricts access to the funds until the maturity date of the investment. CDs are generally issued by commercial banks.

CDs are issued by the bank and are guaranteed by the government. So even if the bank goes bankrupt the investor's money is guaranteed to a certain extent.

Flipping and renting are subjected to market fluctuations while bonds are not insured.

We know that the time difference between India and USA is 9 hrs 30 min.

India is 9:30 hrs ahead of USA.

Time in India = 4:15 + 9:30 = 13:45 PM.

Required Time after 18 hrs = 13:45 + 18 hrs = 7:45 AM.

Hence it is 7:45 AM on the next morning.

Answer 1:
c) Uncle
R is Uncle to D.

Answer 2:
a) JRT
JRT are one each from the same generations.

Number of squares in the given figure is

16 + 9 + 19 + 1 = 45.

Homer's literature had created the foundation for literature and was influential in his time and the future. And they are credited as foundational components of the Western worldview.