Considering June 5th, 2022, Sunday, as the reference date (the day UPSC CSE prelims 2022 was conducted), we can determine the Sundays for June 2099 as well.

Each regular year consists of 364 days plus one additional day, while a leap year consists of 364 days plus two additional days.

So, on June 5th, 2023, it will be Monday (+1 day).

On June 5th, 2024, it will be Wednesday (+2 days).

The difference between the two years is 2099 – 2022 = 77 years.
The number of leap years within this period is 77/4 = 19 (quotient).

Thus, until 2099, there will be 58 regular years and 19 leap years.
The total number of days to be added is (58 * 1) + (19 * 2) = 58 + 38 = 96 days.

When we divide 96 by 7, we get a remainder of 5.

Therefore, on June 5th, 2099, it will be Sunday + 5 = Friday.

Thus, June 7th, 2099, will be a Sunday.