Answer: A

Explanation:

Recently, with rising water levels in the Sardar Sarovar dam due to heavy rain and releases from the Omkareshwar dam, authorities opened nine radial gates by 1.5 meters. Sardar Sarovar Dam (SSD) is a concrete gravity dam built on the Narmada River in Gujarat's Narmada district. Hence, statement 1 is incorrect.

Sardar Sarovar Dam is the third-highest concrete dam (after Bhakra in Himachal Pradesh and Lakhwar in Uttar Pradesh) in India. It is also the second largest gravity dam in the world in terms of the volume of concrete used, after the Grand Coulee Dam in the United States. Hence, statement 2 is incorrect.

Sardar Sarovar Dam is part of the Narmada Valley Project and it was conceived in 1979 to address agricultural and power crisis issues in the state. Hence, statement 3 is correct.

Answer: A

Explanation:

Recently, biotechnologists at Guru Gobind Singh Indraprastha University found significant variation in nitrogen use efficiency (NUE) among popular rice varieties.  Nitrogen-Use Efficiency (NUE) refers to the yield of a crop relative to the amount of nitrogen, both natural and artificial, available to it. Nitrogen-use efficiency is the efficiency with which cultivated rice varieties use nitrogen. Hence, statement I is correct.

Nitrogen-use efficiency is calculated as the ratio of nitrogen used to harvest and a higher number indicates low wastage. It could lead to the development of high-yielding, low-nitrogen rice strains, reducing fertilizer costs and pollution. Hence, statement II is correct.

Hence, statements I and II both are correct and statement II is the correct explanation of statement I. Hence, option (a) is correct.

Answer: C

Explanation:

After a 7.1-magnitude earthquake hit southern Japan on August 8, the meteorological agency issued its first-ever "megaquake advisory." A megaquake is a theoretical type of earthquake with a magnitude greater than 10. Such an event is practically impossible on Earth due to the absence of fault lines large enough to produce a megaquake. Hence, statement 1 is correct.

Megaquake could drastically alter the topology of continents. It could lead to catastrophic global damage and potentially cause mass extinctions on Earth. Hence, statement 2 is correct.

Answer: C

Explanation:

On August 12, 2004, Perseid meteors streaked across the night sky near Amman, Jordan, in the early hours. The Perseid meteor shower is an annual event that typically starts in July and lasts until late August, with peak activity between August 11 and 13. Hence, statement 1 is correct.

The shower is caused by Earth passing through a cloud of debris left behind by Comet Swift-Tuttle, which takes 133 years to orbit the sun. The debris, called the Perseid cloud, stretches along the comet's orbit and is about 27 km wide. Hence, statement 2 is correct.

Answer: A

Explanation:

Vikram Sarabhai (12 August 1919 – 30 December 1971), an Indian physicist and astronomer who initiated space research and helped to develop nuclear power in India, was born in Ahmedabad, Gujarat. He was also often referred to as the "Father of the Indian Space Program". Vikram Sarabhai founded the Physical Research Laboratory in Ahmedabad in 1947, which began its operations at his residence, RETREAT, with cosmic rays as its first research focus. Hence, option (a) is correct.