Science & Technology – UPSC Prelims PYQs

Assertion (A): A stick is dipped in water in a slanting position. If observed sideways, the stick appears short and bent at the surface of water.

Reason (R): The light coming from the stick undergoes scattering from water molecules giving the stick a short and bent appearance.

Assertion (A): A piece of copper and a piece of glass are heated to the same temperature. When touched, thereafter, the copper piece appears hotter than the glass piece.

Reason (R): The density of copper is more than that of glass.

Assertion (A): The boiling point of water decreases as the altitude increases.

Reason (R): The atmospheric pressure increases with altitude.

When light waves pass from air to glass, the variables affected are

When water is heated from 0 °C to 10 °C, its volume

Consider the following statements: In a nuclear reactor, self-sustained chain reaction is possible, because I. More neutrons are released in each of the fission reactions. II. The neutrons immediately take part in the fission process. III. The fast neutrons are slowed down by Graphite. IV. Every neutron released in the fission reaction initiates further fission.

Which of these statements are correct?

Match List I with List II

and select the correct answer using the codes given below the Lists:

List I (Characteristic) I. Zero mass II. Fractional charge III. Fractional spin IV. Integral spin

List II (Particle) A) Positron B) Neutrino C) Quark D) Phonon

Who is the scientist in whose honour the “Chandra” X-ray telescope has been named?

The mass of a body on Earth is 100 kg (acceleration due to gravity, gₑ = 10 m/s²). If acceleration due to gravity on the Moon = gₑ/6, then the mass of the body on the moon is

Consider the following statements: A simple pendulum is set into oscillation. Then I. The acceleration is zero when the bob passes through the mean position. II. In each cycle the bob attains a given velocity twice. III. Both acceleration and velocity of the bob are zero when it reaches its extreme position during its oscillation. IV. The amplitude of oscillation of the simple pendulum decreases with time.

Which of these statements are correct?

A radioactive substance has a half-life of four months. Three fourth of the substance would decay in

Assertion (A): A chemical reaction becomes faster at higher temperatures.

Reason (R): At higher temperatures, molecular motion becomes more rapid.

Which of the following is correct?

Which one of the following is NOT radioactive?

Which one of the following is the correct sequence in increasing order of molecular weights of the hydrocarbons?

In an atom, the order of filling up of the orbitals is governed by

An aqueous solution of copper sulphate is acidic in nature because the salt undergoes

Consider the following statements with reference to the Periodic Table of chemical elements: I. Ionisation potential gradually decreases along a period. II. In a group of elements, electron affinity decreases as the atomic weight increases. III. In a given period, electronegativity decreases as the atomic number increases.

Which of these statement(s) is/are correct?

Which of the following cell organelles play the most significant role in protein synthesis?

Assertion (A): Scientists can cut apart and paste together DNA molecules at will, regardless of the source of the molecules.

Reason (R): DNA fragments can be manipulated using restriction endonucleases and DNA ligases.

Which of the following is correct?

The cellular and molecular control of programmed cell death is known as

Which organelle in the cell, other than nucleus, contains DNA?

Epiphytes are plants which depend on other plants for

Antigen is a substance which

Which of the following features of DNA makes it uniquely suited to store and transmit genetic information from generation to generation?

The American multinational company, Monsanto has produced an insect-resistant cotton variety that is undergoing field-trials in India. A toxin gene from which ONE of the following bacteria has been transferred to this transgenic cotton?

Match List I with List II

and select the correct answer using the codes given below the Lists:

List I (Bone) I. Breast-bone II. Collar-bone III. Knee-cap IV. Shoulder blade

List II (Name) A) Clavicle B) Patella C) Scapula D) Sternum

Consider the following statements: I. Tapeworm is a hermaphrodite. II. Round-worm has separate sexes. III. Filaria is caused by a nematode. IV. Guinea worm is an annelid.

Which of these are correct?

Match List I with List II

and select the correct answer using the codes given below the Lists:

List I (Achievement in genetics) I. Discovery of transduction and conjugation in bacteria II. Establishing the sex-linked inheritance III. Isolation of DNA polymerase from E. coli IV. Establishing the complete genetic code

List II (Scientists) A) Khurana B) Kornberg C) Lederberg D) Morgan E) Ochoa

“Athlete’s Foot” is a disease caused by

In the eye donation, which part of the eye is transplanted from the donor?

A man whose blood group is not known meets with a serious accident and needs blood transfusion immediately. Which one of the blood groups mentioned below and readily available in the hospital will be safe for transfusion?

“Metastasis” is the process by which

Match List I with List II

and select the correct answer using the codes given below the Lists:

List I (Substance) I. Ptyalin II. Pepsin III. Renin IV. Oxytocin

List II (Physiological role) A) Converts angiotensinogen in blood into angiotensin B) Digests starch C) Digests proteins D) Hydrolyses fats E) Induces contraction of smooth muscles

Which one of the following does a TV remote control unit use to operate a TV set?

A noise level of 100 decibels would correspond to

A ‘black hole’ is a body in space which does not allow any radiation to come out. This property is due to its

The memory of a computer is commonly expressed in terms of Kilobytes or Megabytes. A byte is made up of

Consider the following features of newer models of motor cars: I. Radial tyres II. Streamlined body III. Multipoint fuel injection IV. Catalytic converter with exhaust

Which of these features make the newer models of motor cars more fuel-efficient?

Fluorescent tubes are fitted with a choke. The choke coils

For reproducing sound, a CD (Compact Disc) audio player uses a

When a CD (Compact Disc used in audio and video systems) is seen in sunlight, rainbow-like colours are seen. This can be explained on the basis of the phenomenon of

Assertion (A): A man standing on a completely frictionless surface can propel himself by whistling.

Reason (R): If no external force acts on a system, its momentum cannot change.

Assertion (A): In a motion picture, usually 24 frames are projected every second over the whole length of the film.

Reason (R): An image formed on the retina of eye persists for about 0.1 s after the removal of stimulus.

Assertion (A): Small glass beads fixed on traffic signals glow brightly when light falls upon them.

Reason (R): Light is totally reflected when the angle of incidence exceeds a certain critical value and light travelling in a denser medium is reflected back into a rarer medium.

The stones formed in human kidney consist mostly of

Most of the explosions in mines occur due to the mixing of

Match List I with List II

and select the correct answer using the codes given below the Lists:

List I I. German Silver II. Solder III. Bleaching Powder IV. Hypo

List II A) Tin B) Nickel C) Sodium D) Chlorine

Codes:

Which one of the following materials is very hard and very ductile?

Soft drinks such as colas contain significant quantities of

Aluminium surfaces are often “anodized”. This means the deposition of a layer of