UPSC 2003 Science and Technology Questions with Answers

Explanation

METSAT (renamed as Kalpana - 1) was the first in the series of exclusive meteorological satellites built by ISRO.

Statement 1 is correct: India successfully launched its first full-fledged meteorological satellite, METSAT using the PSLV-C4 rocket. It was India’s first dedicated meteorological satellite, designed to monitor weather conditions and cyclone development in the Indian Ocean region.

Statement 2 is correct: PSLV-C4 carried METSAT (1,060 kg) into a geosynchronous transfer orbit (GTO), marking the first time PSLV carried a payload exceeding 1000 kg into GTO. This demonstrated ISRO’s ability to deploy heavier payloads into higher orbits, advancing India’s space technology capabilities.

Explanation

Assertion (A) is true: Weight is the force of gravity acting on an object, and gravity weakens as the distance from the Earth>s center increases. Since altitude represents a greater distance from the Earth>s center, the force of gravity and thus the weight of the body diminish. Reason (R) is true: The Earth is not a perfect sphere, being slightly flattened at the poles and bulging at the equator, this fact does not primarily explain the decrease in weight with altitude. The primary reason lies in the inverse square law of gravity, which states that the force of gravity between two objects decreases proportionally to the square of the distance between them. Hence, Reason (R) does not correctly explain the Assertion (A).

Explanation

Statement 1 is correct: When a vehicle takes a sharp turn at high speed, the centrifugal force may push the vehicle outwards. This can cause the vehicle to tilt outwards and potentially overturn about its outer wheels.

Statement 2 is incorrect: This is less likely to happen. The centrifugal force pushes the vehicle outwards, not inwards.

Statement 3 is correct: If the friction between the tires and the road is insufficient to provide the necessary centripetal force, the vehicle may skid outwards, away from the center of the turn.

Statement 4 is incorrect: Skidding typically occurs outwards, not inwards, due to the centrifugal force.

Explanation

When the oil tanker accelerates forward, the oil inside experiences an inertial force (pseudo force) acting in the opposite direction to the acceleration. This causes the free surface of the oil to tilt. 1. The rear end of the tanker has larger depth because the inertial force pushes the oil backward.

2. The front end has smaller depth as the oil moves away from it. Thus, The free surface of the oil becomes inclined, with the rear end having a larger depth

Explanation

Statement 1 is incorrect: Steam at 100°C contains significantly more heat than boiling water at 100°C. This is because steam has absorbed additional energy in the form of latent heat of vaporization which is the energy required to convert water at 100°C into steam at the same temperature without changing its temperature.

Statement 2 is incorrect: The latent heat of fusion of ice (the energy required to convert ice at 0°C to water at 0°C) is approximately 334 kJ/kg while the latent heat of vaporization of water (the energy required to convert water at 100°C to steam at 100°C) is approximately 2260 kJ/kg.

Statement 3 is correct: In an air-conditioner the refrigerant absorbs heat from the room air at the evaporator coils and cools the air. This heat is then transported to the condenser coils, where it is released to the outside environment. This process is based on the principles of thermodynamics and the refrigeration cycle.

Explanation

The diffusion of light in the atmosphere occurs mainly due to dust particles and aerosols, which scatter sunlight in all directions. This scattering, known as Mie scattering, happens when particles like dust or water droplets are comparable in size to the wavelength of light, scattering all wavelengths almost equally. It causes the sky to appear uniformly bright and ensures visibility even in shadows. Other aerosols like Water Vapors, Smoke, etc can also contribute to the diffusion effect. However, dust particles are the most prominent cause in this context.

Explanation

Option (c) is incorrect: Humidity (water vapor) actually increases the speed of sound in air. This is because water molecules are lighter than nitrogen and oxygen molecules, reducing the overall density of the air. The speed of sound in humid air is higher than in dry air at the same temperature. Options (a), (b) and (d) are correct:

The velocity of sound in air increases with temperature because higher temperatures increase the energy of air molecules, allowing sound to travel faster. The velocity of sound in air is independent of pressure at constant temperature since both pressure and density change proportionally, leaving the speed unchanged. The velocity of sound is unaffected by amplitude and frequency as it depends only on the medium>s properties like temperature, density, and composition.

Explanation

Ionic compounds are chemical compounds composed of positively and negatively charged ions held together by strong electrostatic forces of attraction.

Statement 1 is correct: Ionic compounds generally dissolve in water due to its high polarity, but alcohols are less polar compared to water, which makes most ionic compounds insoluble in alcohol.

Statement 2 is incorrect: In the solid state, the ions in ionic compounds are fixed in a rigid lattice structure and cannot move freely, which prevents the conduction of electricity.

Explanation

Option (a) is correct: The magnetic quantum number of an element specifies the orientation of an orbital in space relative to an external magnetic field. It determines the number of orbitals and their spatial orientation within a given subshell (defined by the azimuthal quantum number, l). Options (b), (c) and (d) are incorrect: Shape is determined by the azimuthal quantum number; Size is determined by the principal quantum number; Spin is determined by the spin quantum number, which specifies the spin orientation of the electron.

Explanation

Option (a) is correct: Liquid sodium is used as a coolant in certain types of nuclear reactors, particularly fast breeder reactors. Sodium is an effective coolant because of its high thermal conductivity and low neutron absorption properties, which are ideal for cooling the reactor core. Options (b), (c) and (d) are incorrect:

Dental amalgams are typically made of silver, mercury, and other metals. Calcium carbonate is not a must-include ingredient in toothpastes. Though it is sometimes used in toothpaste as an abrasive that helps remove plaque, stains, and debris from teeth. Bordeaux mixture is made from copper sulfate and lime (calcium hydroxide). It is used as a fungicide and pesticide in agriculture to prevent fungal diseases like downy mildew in crops. Zinc amalgam is not commonly used in dental fillings, although zinc oxide is sometimes used in dental cements and temporary fillings.