The construction of the world’s largest optical telescope has started in northern Chile, which is expected to begin operating in 2024. The Extremely Large Telescope (ELT) is being built by the European Southern Observatory (ESO) and will have a main mirror that is 39m in diameter. The telescope will be positioned on top of Cerro Armazones – a 3046-metre long mountain Chile. It will tackle a wide range of scientific challenges, including probing Earth-like exoplanets for signs of life, studying the nature of dark energy and dark matter, and observing the universe’s early stages to explore humans’ origins.

48, 54, 63, 81 and 105 are divisible by 3 but not 35.

Lowest 4-digit number is 1000.
LCM of 3, 4 and 5 is 60.
Dividing 1000 by 60, we get the remainder 40. Thus, the lowest 4-digit number that exactly divisible by 3, 4 and 5 is 1000 + (60 - 40) = 1020.
Now, add the remainder 2 that's required. Thus, the answer is 1022.

3/15 + 4/16 + x/24 = 1

⇒x=1315

Mumbai has been ranked the world's second most densely populated city with 31,700 people per sq km, by the World Economic Forum (WEF) citing UN Habitat Data. Bangladesh's capital Dhaka topped the list with 44,500 people per sq km. Rajasthan's Kota has been ranked the world's seventh most densely populated city with 12,100 people per sq km.

The Human Resource Development Ministry and the External Affairs Ministry launched an online verification portal to make the document verification process easier for students who planning to study abroad. The Central Board of Secondary Education’s (CBSE) academic repository of degrees and certificates “Parinam Manjusha” was also involved in the project of creating “eSanad”.

Indian Oil Corp (IOC) has overtaken Oil and Natural Gas Corp (ONGC) to become India’s most profitable state-owned company. IOC, which has for decades been India’s biggest company by turnover, posted a 70 per cent jump in net profit to Rs 19,106.40 crore in the financial year ended March 31, 2017.

Given that 2.12.91 is the first Tuesday
Hence we can assume that 4.12.91 is the first Thursday

If we add 7 days to 4.12.91, we will get second Thursday
If we add 14 days to 4.12.91, we will get third Thursday
If we add 21 days to 4.12.91, we will get fourth Thursday

=> fourth Thursday = (4.12.91 + 21 days) = 25.12.91.