science & tech MCQ section 5 MCQ Questions & Answers Detailed Explanation

Answer: (d)

The Polar Satellite Launch Vehicle (PSLV) is an expendable launch system developed and operated by the Indian Space Research Organisation (ISRO).

It was developed to allow India to launch its Indian Remote Sensing (IRS) satellites into sun-synchronous orbits, a service that was, until the advent of the PSLV, commercially viable only from Russia. PSLV can also launch small size satellites into geostationary transfer orbit (GTO).

The PSLV has launched 55 satellites/spacecraft (26 Indian and 29 Foreign Satellites) into a variety of orbits so far.

Note: The Polar Satellite Launch Vehicle, commonly known by its abbreviation PSLV, is an expendable launch system developed and operated by the Indian Space Research Organization (ISRO).

On Feb 15, 2017 PSLV-C37 Successfully Launches 104 Satellites in a Single Flight.

Answer: (a)

Israeli built Spike anti-tank missile is a third generation fire and forget system.

Answer: (d)

The total annual external dose from sources in soil and cosmic rays in Mumbai, Kolkata, Chennai, Delhi and Bengaluru is 0.484, 0.81, 0.79, 0.70 and 0.825 milligray respectively. Gray is a unit for absorbed dose; when the radiation energy imparted to a kg of material is one joule, it is called a gray.

Since gray is very large, milligrays (one-thousandth of a gray), and microgray (one-millionth of a gray), are commonly used. Cosmic rays come from outer space. Their intensity at a place depends on the altitude. Cosmic rays alone contribute 0.28 milligrays at the first three cities as they are at sea level; the column of air helps to reduce their intensity.

At high altitudes, the protection from the column of air is less. The cosmic ray contributions are higher at 0.31 milligray and 0.44 milligray respectively at Delhi and Bengaluru as these cities are at altitudes of 216 metres and 921 metres. Air passengers receive 5 micrograys per hour from cosmic rays. Parts of Kerala and Tamil Nadu are high background radiation areas (HBRA) because of the presence of large quantities of monazite in the soil.

Thorium content in monazite ranges from 8-10.5 per cent. Researchers found that the radiation levels in 12 Panchayats in Karunagappally varied between 0.32 to 76 milligrays per year; the levels in 90 per cent of over 71,000 houses were more than one milligray per year.

Answer: (d)

The Lakshya is an Indian remotely piloted high speed target drone system developed by the ADE of DRDO. It is a Pilotless Target Aircraft (PTA). So far 23 PTA have been inducted in the defence system. It has a range of 150 km.

Answer: (c)

Nuclear weapons-capable, surface-to-surface Prithvi-II missile was successfully flight-tested for its full range of 350 km by the Strategic Forces Command (SFC) personnel on June 9, 2011.

The nine-metre tall Prithvi-II, the first indigenously built surface-to-surface strategic missile, was fired from a mobile launcher from Launch Complex-III at the Integrated Test Range at Chandipur in Odisha.

Note: Prithvi is a tactical surface-to-surface short-range ballistic missile (SRBM) developed by DRDO of India under the Integrated Guided Missile Development Program. The Prithvi missile project encompassed developing three variants for use by the Indian Army, Indian Air Force and the Indian Navy Prithvi I class is a surface-to-surface missile having a maximum warhead mounting capability of 1,000 kg, with a range of 150 km (93 mi).

It has an accuracy of 10–50 m (33–164 ft) and can be launched from transporter erector launchers. This class of Prithvi missiles was inducted into the Indian Army in 1994.

As Per (DRDO) Chief Avinash Chander the tactical 150 km-range Prithvi missile will be replaced with the Prahaar missile. Prithvi II class is also a single-stage liquid-fueled missile having a maximum warhead mounting capability of 500 kg, but with an extended range of 250 km (160 mi).

It was developed with the Indian Air Force being the primary user. According to news sources, the range is now increased to 350 km (220 mi) and the payload capacity now ranges between 500 – 1000 kg. Prithvi III class is a two-stage surface-to-surface missile. The first stage is solid-fueled with a 16 metric ton-force (157 KN) thrust motor.

The second stage is liquid-fueled. The missile can carry a 1,000 kg warhead to a distance of 350 km (220 mi) and a 500 kg warhead to a distance of 600 km (370 mi) and a 250 kg warhead up to a distance of 750 km (470 mi). Prithvi III or Dhanush was again tested on November 26, 2015, from INS Subhadra in the Bay of Bengal.

Answer: (c)