SSC CGL Top 100 Important Questions from General Science
SSC CGL Top 100 Important Questions from General Science
-
- What is the focal length of a concave lens with number -5D?
[A] 5 cm
[B] 10 cm
[C] 15 cm
[D] 20 cm
Correct Answer: D [20 cm]
Notes:
A concave lens is a type of lens that has a thinner center than edges, and it is sometimes called a diverging lens because it spreads out light rays that are parallel to its axis. The focal length of a lens is a measure of its ability to focus light, and it is defined as the distance from the lens to the point where the light rays converge. In the case of a concave lens with a power of -5D, the focal length would be equal to 1/5 of a meter, or 20 centimeters.
2. Which among the following defines cohesive force?
[A] the force of attraction acting between the molecules of the same material
[B] the force of attraction acting between the molecules of different material
[C] the force of attraction acting between the atoms of the same material
[D] None of the above
Correct Answer: A [the force of attraction acting between the molecules of same material]
Notes:
The force of attraction acting between the molecules of same material is known as cohesive force. Cohesive force is the action or property of like molecules sticking together, being mutually attractive.
3. Which among the following waves are used in the gemstone industry to change white topaz into blue topaz?
[A] X-Rays
[B] Gamma Rays
[C] Alpha Radiation
[D] Beta Radiation
Correct Answer: B [Gamma Rays]
Notes:
Gamma rays is commonly used in the gemstone industry to change white topaz into blue topaz. Because white topaz is heat-treated to turn into blue topaz, the value of blue topaz is often decreased.
4. The force that binds the neutrons and protons in a nucleus is called as:
[A] Weak Nuclear Force
[B] Strong Nuclear Force
[C] Electromagnetic Force
[D] Gravitational Force
Correct Answer: B [Strong Nuclear Force]
Notes:
Strong Nuclear Force is the force that binds the neutrons and protons together in a nucleus. Nuclear forces are the strongest forces in nature are 10^38 times stronger than gravitational forces. Nuclear forces have the shortest range and operate within the nucleus only.
SSC CGL Top 100 Important Questions from General Science
5. A projectile will achieve maximum horizontal range at which angle?
[A] 90°
[B] 60°
[C] 45°
[D] 30°
Correct Answer: C [45°]
Notes:
A projectile will achieve maximum horizontal range when it is projected at an angle of 45°. This concept of maximum horizontal range is used by athletes in long jump, javelin throw, cricket ball throw etc
SSC CGL Top 100 Important Questions from General Science
6. Which of these is the cause of Friction?
[A] Roughness of surfaces in contact
[B] Force of adhesion between the molecules of the surfaces in contact
[C] Both a and b
[D] None of the above
Correct Answer: C [Both a and b]
Notes:
Friction is the force that opposes the relative motion between the two surfaces of objects in contact. Friction is caused due to: 1. Roughness of surfaces in contact 2. Force of adhesion between the molecules of the surfaces in contact
7. What is the average power consumption of a heartbeat in an adult?
[A] 1.2 watt
[B] 112.5 watt
[C] 200 wat
[D] 500 watt
Correct Answer: A [1.2 watt]
Notes:
Average power consumption by an adult in some of the common processes/activities: 1. Heartbeat – 1.2 watt 2. Sleeping – 75 watt 3. Slow walking – 200 watt 4. Bicycling – 500 watt
8. Water does not fall out of a glass when it is inverted inside a satellite, which is orbiting very close to the earth’s surface. Which of the following is the best reason for this?
[A] The earth does not exert any force on the water
[B] The earth’s force of attraction on the water is exactly balanced by the force created by the satellites
[C] The water and the glass have the same acceleration due to gravity
[D] The gravitational attraction between the glass and the water balances the earth’s attraction on the
Correct Answer: C [The water and the glass have the same acceleration due to gravity]
Notes:
Water does not fall out of a glass when it is inverted inside a satellite, which is orbiting very close to the earth’s surface. The reason for this is that the water and the glass have the same acceleration due to gravity, equal to g, towards the centre of the earth. Hence there is no relative motion between them.
9. Which of the following strains is produced in a body if the deforming force produces a change in the shape of the body without changing its volume?
[A] Linear
[B] Volumetric
[C] Shearing
[D] All of the above
Correct Answer: C [Shearing]
Notes:
If the deforming force produces a change in the shape of the body without changing its volume, the strain produced in the body is called as shearing strain. Shearing strain is defined as an angle in radians through which a plane perpendicular to the fixed surface of the cubical body gets turned under the effect of tangential force.
10. Who invented the mercury barometer?
[A] Blaise Pascal
[B] Daniel Bernoulli
[C] Albert Einstein
[D] Evangelista Torricelli
Correct Answer: D [Evangelista Torricelli]
Notes:
Evangelista Torricelli devised for the first time a method for measuring atmospheric pressure. A long glass tube closed at one end and filled with mercury is inverted into a trough of mercury. This device is known as a ‘mercury barometer’.
SSC CGL Top 100 Important Questions from General Science
11. Water does not fall out of a glass when it is inverted inside a satellite, which is orbiting very close to the earth’s surface. Which of the following is the best reason for this?
[A] The earth does not exert any force on the water
[B] The earth’s force of attraction on the water is exactly balanced by the force created by the satellites
[C] The water and the glass have the same acceleration due to gravity
[D] The gravitational attraction between the glass and the water balances the earth’s attraction on the
Correct Answer: C [The water and the glass have the same acceleration due to gravity]
Notes:
Water does not fall out of a glass when it is inverted inside a satellite, which is orbiting very close to the earth’s surface. The reason for this is that the water and the glass have the same acceleration due to gravity, equal to g, towards the center of the earth. Hence there is no relative motion between them.
SSC CGL Top 50 Important Questions from General Science
12. What is the unit of Stress?
[A] N/m
[B] Kg/m
[C] Nm
[D] It has no units
Correct Answer: A [N/m]
Notes:
If an external force F is applied on the area A of a body then, Stress is given by Force/Area Units of Stress: S.I unit: N / m C.g.s unit: dyne / cm
13. What is the stress known as when there is a relative displacement between various layers of a solid?
[A] Tangential
[B] Linear
[C] Lateral
[D] Longitudinal
Correct Answer: A [Tangential]
Notes:
When successive layers of solid move on each other i.e. when there is a relative displacement between various layers of solid, the stress produced is called as Tangential stress.
14. What is Young’s Modulus?
[A] ratio of longitudinal strain to normal stress
[B] product of normal stress of longitudinal strain
[C] ratio of normal stress to longitudinal strain
[D] ratio of normal stress to lateral strain
Correct Answer: C [ratio of normal stress to longitudinal strain]
Notes:
Young’s Modulus is defined as the ratio of normal stress to longitudinal strain within limit of proportionality. Y = normal stress/longitudinal strain
15. Which of the following is equal to the upthrust of the body?
[A] mass of body
[B] weight of liquid
[C] weight of liquid displaced
[D] density of liquid
Correct Answer: C [weight of liquid displaced]
Notes:
Archimedes Principle: when a body is immersed partially or completely in a liquid, it experiences an upthrust, which is equal to the weight of the liquid displaced by the body.
SSC CGL Top 100 Important Questions from General Science
16. What is the shape of the meniscus when the angle of contact is greater than 90°?
[A] Concave
[B] Convex
[C] Plane
[D] None of the above
Correct Answer: B [Convex]
Notes:
When the angle of contact is greater than 90°, the shape of the meniscus is convex. When the angle of contact is less than 90°, the shape of the meniscus is concave. When the angle of contact is equal to 90°, the shape of the meniscus is plain.
SSC CGL Top 100 Important Questions from General Science
17. Which is correct about the height of a capillary column of a liquid, at a particular temperature, as per Jurin’s law?
[A] equal to the diameter of the tube
[B] directly proportional to the diameter of the tube
[C] inversely proportional to the diameter of the tube
[D] half of the diameter of the tube
Correct Answer: C [inversely proportional to the diameter of the tube]
Notes:
Jurin’s law: the height of a capillary column of a liquid at a particular temperature is inversely proportional to the diameter of the tube.
18. What is the relationship between excess pressure and the radius of the bubble?
[A] are equal in value
[B] inversely proportional to each other
[C] directly proportional to each other
[D] no relationship
Correct Answer: B [inversely proportional to each other]
Notes:
Excess pressure is inversely proportional to the radius of the bubble (or drop). It means that the pressure inside a smaller bubble is higher than inside a larger bubble.
19. What is the unit of surface tension in c.g.s system?
[A] N/m
[B] dyne/cm
[C] erg/cm
[D] dyne cm
Correct Answer: B [dyne/cm]
Notes:
The unit of surface tension is the S.I system is N/m and in the c.g.s system is dyne/cm. It is represented by T = force/length.
SSC CGL Top 100 Important Questions from General Science
20. What is the density of air at room temperature?
[A] 1.41
[B] 1.75
[C] 1.29
[D] 1.9
Correct Answer: C [ 1.29]
Notes:
The density of air at room temperature near the surface of the Earth is approximately 1.29 kg/m3
21. Which of the following is a suitable material for making a permanent magnet?
[A] alnico
[B] cobalt steel
[C] ticonal
[D] All of the above
Correct Answer: D [All of the above]
Notes:
Soft iron, alnico, cobalt steel, and ticonal are some of the suitable materials for permanent magnets.
22. Which of the following metal foils was used in the Rutherford’s alpha particle scattering experiment?
[A] Copper
[B] Silver
[C] Gold
[D] Aluminium
Correct Answer: C [Gold]
Notes:
Rutherford directed beams of alpha particles (which are the nuclei of helium atoms and hence positively charged) at thin gold foil and noted how the alpha particles scattered from the foil.
23. What is the output of an AND gate when both the inputs are 0?
[A] 0
[B] 1
[C] Either 0 or 1
[D] 2
Correct Answer: A [0]
Notes:
The AND gate is a basic digital logic gate that gives a LOW output If none or not all inputs to the AND gate are HIGH.
24. What is the charge of a p-type semiconductor?
[A] Positive
[B] Negative
[C] Neutral
[D] None of the above
Correct Answer: C [Neutral]
Notes:
The number of free electrons is exactly equal to the total number of holes and positively charged ions and a semiconductor, whether intrinsic or doped, is electrically neutral
25. Why the metals are good conductors of electricity?
[A] Because they have free electrons
[B] Because they have free protons
[C] Because they have free neutrons
[D] None of the above
Correct Answer: A [ Because they have free electrons ]
Notes:
Metals are good conductors of electricity, because they have free electrons. These free electrons act as charge carriers in the metallic structure, allowing electric current to flow through the metal. Metals are good conductors of electricity, because they allow electric charge to flow freely through them.
SSC CGL Top 100 Important Questions from General Science
26. Why does a bird sitting on a high tension electric wire do not get electrocuted?
[A] The body is earthed
[B] It has high resistance
[C] Its feet are good insulator
[D] It does not form a closed path for the flow of electricity
Correct Answer: D [It does not form a closed path for the flow of electricity]
Notes:
Birds can sit on high-voltage power lines without getting electrocuted because they are not good conductors of electricity. When a bird sits on a wire, it doesn’t touch the ground or anything in contact with the ground. This means there is no potential difference for electricity to flow.
However, if a bird touches a power line and equipment or other metal that is grounded, it gives electricity a path to the ground, and the bird could be shocked. Birds could also be shocked if they flap their wings and touch another electric wire with a different voltage.
Birds can also be in danger if they sit on the wooden poles supporting the wires. These poles are buried in the ground, so they have a low electrical potential. If a bird were to sit on the pole and simultaneously touch a wire, the current would flow from the high potential wire through the bird’s body and into the low potential ground.
27. What is the minimum distance (in metres) required to hear an echo?
[A] 10
[B] 13
[C] 21
[D] 17
Correct Answer: D [17]
Notes:
The velocity of sound in dry air is approximately 343 m/s at a temperature of 25 °C. Therefore, the reflecting object must be more than 17.2m from the sound source for echo to be perceived by a person located at the source.
SSC CGL Top 50 Important Questions from General Science
28. Which of the following devices is used to measure humidity?
[A] Hydrometer
[B] Hygrometer
[C] Anemometer
[D] Psycho Meter
Correct Answer: B [Hygrometer]
Notes:
A hygrometer is a weather instrument used to measure the amount of humidity in the atmosphere. There are two main types of hygrometers – a dry and wet bulb psychrometer and a mechanical hygrometer.
29. At which of the following place, weight of an object is maximum?
[A] At tropic of cancer
[B] At poles
[C] At tropic
[D] At equator
Correct Answer: B [At poles]
Notes:
The weight of an object is minimum when it is placed at the center of the earth because when an object is in the center, experiences gravitational pull from all directions & the weight of an object maximum on earth is on the poles.
30. Neil Armstrong was the first person to reach on the moon. While walking on the moon what happens to his mass and weight?
[A] His mass remained the same but his weight increased
[B] His mass remained the same but weight decreased
[C] His mass as well as weight decreased
[D] His mass increased but weight remained the same
Correct Answer: B [His mass remained the same but weight decreased]
Notes:
Mass is a measure of the amount of matter that an object has, or how much “stuff” it is made up of. Weight is a measure of how much gravity pulls on a mass or object. Mass doesn’t change when gravity changes. The mass on the moon would be the same as the mass on earth. The force due to gravity is 1/6 that of Earth, so he will weigh 1/6 of Earth weight.
SSC CGL Top 100 Important Questions from General Science
31. Which of these is an acceptor impurity?
[A] Phosphorus
[B] Arsenic
[C] Antimony
[D] Indium
Correct Answer: D [Indium]
Notes:
A donor impurity donates an electron to the conduction band. An acceptor impurity like indium has only electrons in its valence shell. It can accept an electron from nearest atom as it has a vacancy of electron.
32. How does a semiconductor behave at absolute zero temperature?
[A] like an insulator
[B] like a conductor
[C] depends on the material
[D] None of the above
Correct Answer: A [like an insulator]
Notes:
At or close to absolute zero a semiconductor behaves like an insulator. When an electron gains enough energy to participate in conduction (is “free”), it is at a high energy state. When the electron is bound, and thus cannot participate in conduction, the electron is at a low energy state.
33. Atmospheric pressure exerted on earth is due to the which of the following reasons?
[A] Rotation of earth
[B] Revolution of earth
[C] Gravitational pull
[D] Uneven heating of earth
Correct Answer: C [Gravitational pull]
Notes:
The atmospheric pressure at the surface of the Earth is due to gravitational pull of the earth and is about 14.7 psi. That means that the weight of a column of air which has a cross section of 1 square inch and which stretches from the surface of the Earth to space is 14.7 pounds.
34. Which instrument measures and records the relative humidity of air?
[A] Hydrometer
[B] Hygrometer
[C] Lactometer
[D] Barometer
Correct Answer: B [Hygrometer]
Notes:
A hygrometer is an instrument used for measuring the moisture content in the environment. It usually reply on measurements of some other quantity such as temperature, pressure, mass or a mechanical or electrical change in a substance as moisture is absorbed. Modern electronic devices use temperature of condensation, or changes in electrical capacitance or resistance to measure humidity changes.
35. Which of the following have the same unit?
[A] Work and power
[B] Torque and moment of inertia
[C] Work and torque
[D] Torque and angular momentum
Correct Answer: C [Work and torque]
Notes:
The SI unit of work is the Newton-metre or joule (J). A Newton meter is also the SI unit of torque (also called moment or moment of force).
SSC CGL Top 100 Important Questions from General Science
36. What is the Earth’s escape velocity?
[A] 2.8 km/s
[B] 5.6 km/s
[C] 11.2 km/s
[D] 14 km/s
Correct Answer: C [11.2 km/s]
Notes:
In physics, escape velocity is the minimum speed needed for an object to escape from the gravitational influence of a massive body. On the surface of the Earth, the escape velocity is about 11.2 km/s, which is approximately 33 times the speed of sound (Mach 33).
SSC CGL Top 100 Important Questions from General Science
37. Water drops cannot stick to the oily surface due to which of the following?
[A] lack of adhesive force
[B] surface tension
[C] cannot mix each other
[D] water is lighter than oil
Correct Answer: B [surface tension]
Notes:
The separation of oil and water is caused due to the difference in surface tension of the two liquids. The water molecules stick together tightly and does not mix with the oil because water molecules are attracted to each other more strongly, forming an invisible skin of surface tension around each drop as compared to oil drop.
38. The freezing point of fresh water is _______.
[A] 4°C
[B] 3°C
[C] 5°C
[D] 0°C
Correct Answer: D [0°C]
Notes:
The freezing point of water is the temperature at which water changes phase from a liquid to a solid. Under normal conditions, ordinary water freezes at 0‹C, or 32‹F. The temperature may be lower if supercooling occurs or if there are impurities present in the water which could cause freezing point depression to occur. (Raoult’s law).
39. Super cooling stands for cooling of a liquid :
[A] at freezing point
[B] below freezing point
[C] at melting point
[D] above melting point
Correct Answer: B [below freezing point]
Notes:
Supercooling, also known as undercooling, is the process of lowering the temperature of a liquid or a gas below its freezing point without it becoming a solid. A good example of this phenomenon is clouds at high altitude that are an accumulation of supercooled droplets of water below their freezing point. Refrigeration using dry ice is a popular commercial application of supercooling.
40. A hinged door is an example of which class of lever?
[A] Third Class Lever
[B] Second Class Lever
[C] First Class Lever
[D] Cantilever
Correct Answer: B [Second Class Lever]
Notes:
A door belongs to the second class of levers because its pivot (hinge) is at the end, the load (weight of the door) is at the center, while the effort (opening the door) is applied at the other end. A class 2 lever has the resistance or load in the middle, the fulcrum at one end, and the effort at the other.
SSC CGL Top 100 Important Questions from General Science
41. The cooling by a desert Cooler is based on__:
[A] Hot air replacement
[B] Air dehydration
[C] Evaporative Cooling
[D] Air Rehydration
Correct Answer: C [Evaporative Cooling]
Notes:
Nature’s most efficient means of cooling is through the evaporation of water. Desert coolers make use of evaporative cooling that works on the principle of heat absorption by moistures evaporation. As water is evaporated, heat energy is extracted from the air to produce the cooling effect.
42. The quality of a musical note depends on
[A] Fundamental frequency
[B] Amplitude of the wave
[C] Harmonics present
[D] Velocity of sound in the medium
Correct Answer: C [Harmonics present]
Notes:
Sound “quality” or “timbre” describes those characteristics of sound which allow the ear to distinguish sounds which have the same pitch and loudness produced by different sources such as sitar and guitar, drum or dholak, etc. Timbre is mainly determined by the harmonic content of a sound and the dynamic characteristics of the sound such as vibrator and the attack-decay envelope of the sound. Harmonic content is the most important of these.
SSC CGL Top 50 Important Questions from General Science
43. A flying jet possesses which kind of energy?
[A] Potential energy
[B] Kinetic energy
[C] Wind energy
[D] Both kinetic and potential energy
Correct Answer: D [Both kinetic and potential energy]
Notes:
A flying jet possesses both potential and kinetic energies. When it is in flight, it flies at a certain height above the ground and so it is displaced by certain distance and hence it possesses potential energy (energy that is stored because of the position of an object). Besides, it possesses kinetic energy as it is in motion.
44. Time period of a pendulum will ______ at the Moon to that of on the Earth.
[A] remain same
[B] decreases
[C] increases
[D] No option is correct
Correct Answer: C [increases]
Notes:
When the pendulum is taken to the moon, the value of ‘g’ will decrease and hence time period will increase than that of on the Earth.
45. Lamberts law is related to which of the following?
[A] Reflection
[B] Refraction
[C] Interference
[D] Illumination
Correct Answer: D [Illumination]
Notes:
Lambert’s Law states that the intensity of emitted light from a surface is directly proportional to the cosine of the angle between the line of view and the normal to the surface. A Lambertian surface is a surface that follows this rule exactly. In practice, most surfaces are not perfectly Lambertian. A surface which obeys Lambert’s law is said to be Lambertian, and exhibits Lambertian reflectance. Such a surface has the same radiance when viewed from any angle.
SSC CGL Top 100 Important Questions from General Science
46. Lens is made up of which type of glass?
[A] Pyrex glass
[B] Flint glass
[C] Ordinary glass
[D] Cobalt glass
Correct Answer: B [Flint glass]
Notes:
Flint glass is optical glass that has relatively high refractive index and low Abbe number (high dispersion). A concave lens of flint glass is commonly combined with a convex lens of crown glass to produce an achromatic doublet lens because of their compensating optical properties, which reduces chromatic aberration (colour defects).
47. Rainbow is formed due to which of the below phenomena?
[A] refraction and dispersion
[B] scattering and refraction
[C] diffraction and refraction
[D] refraction and reflection
Correct Answer: D [refraction and reflection]
Notes:
A rainbow is an optical phenomenon that is caused by dispersion, refraction, and reflection of light in water droplets resulting in a spectrum of light appearing in the sky. It is caused by light being refracted (bent), dispersed, and then finally reflected from the back surface to be seen by the viewer. To watch a rainbow the position of the sun has a viewer and water droplets in the front. In a rainbow, raindrops in the air cut as a prism.
SSC CGL Top 100 Important Questions from General Science
48. At low temperatures, Lead behaves as a__:
[A] Semiconductor
[B] Superconductor
[C] Insulator
[D] Conductor
Correct Answer: B [Super conductor]
Notes:
Lead, as discovered exhibit superconducting phase transitions at low temperatures of 7.2 Kelvin. At this temperature, the electrical resistivity of lead drops to zero.
49. Which one among the following is not an electromagnetic wave?
[A] X-Ray
[B] R-Ray
[C] Cathode Ray
[D] Infrared Ray
Correct Answer: C [Cathode Ray]
Notes:
In physics, electromagnetic radiation (EMR) refers to the waves (or their quanta, photons) of the electromagnetic field, propagating (radiating) through space carrying electromagnetic radiant energy. It includes radio waves, microwaves, infrared, (visible) light, ultraviolet, X-rays, and gamma radiation only.
50. Sir C. V. Raman was awarded Nobel Prize for his work on:
[A] Light Scattering
[B] Radioactivity
[C] Cryogenics
[D] Sonometer
Correct Answer: A [Light Scattering]
Notes:
Sir C. V. Raman was an Indian physicist whose ground breaking work in the field of light scattering earned him the 1930 Nobel Prize for Physics. He discovered that, when light traverses a transparent material, some of the deflected light changes in wavelength. This phenomenon is now called Raman scattering.