RRB NTPC Science and Technology Basics 1 — Questions and Answers
Question 1: Which instrument is used to measure atmospheric pressure?
- Thermometer
- Hygrometer
- Barometer (Correct answer)
- Anemometer
Correct answer: Barometer
A Barometer is used to measure atmospheric (air) pressure. It was invented by Evangelista Torricelli in 1643.
A Barometer measures atmospheric pressure. Invented by Italian physicist Evangelista Torricelli in 1643, the original mercury barometer used a column of mercury whose height reflected atmospheric pressure. Standard atmospheric pressure = 101,325 Pa (Pascals) = 760 mmHg = 1 atm. Other weather instruments: Thermometer — temperature; Hygrometer — humidity; Anemometer — wind speed; Hydrometer — specific gravity of liquids; Lactometer — purity of milk; Seismograph — earthquake intensity; Richter Scale — earthquake magnitude; Rain gauge — rainfall measurement. Falling barometric pressure indicates approaching bad weather; rising pressure indicates fair weather.
Question 2: The chemical formula of common salt (table salt) is:
- KCl
- CaCl₂
- NaCl (Correct answer)
- MgCl₂
Correct answer: NaCl
Common table salt is Sodium Chloride (NaCl), formed by the ionic bond between sodium (Na) and chlorine (Cl) atoms.
Common salt (table salt) is Sodium Chloride (NaCl). It is an ionic compound formed when sodium (Na, a metal) donates one electron to chlorine (Cl, a non-metal). Other common chemical formulas: KCl = Potassium Chloride; CaCl₂ = Calcium Chloride; NaOH = Sodium Hydroxide (caustic soda); Na₂CO₃ = Washing soda; NaHCO₃ = Baking soda; CaCO₃ = Limestone/Marble/Chalk; H₂SO₄ = Sulfuric acid (battery acid); HNO₃ = Nitric acid; HCl = Hydrochloric acid. For RRB NTPC, memorize the common names and chemical formulas of everyday chemicals.
Question 3: The speed of light in vacuum is approximately:
- 3 × 10⁶ m/s
- 3 × 10⁸ m/s (Correct answer)
- 3 × 10¹⁰ m/s
- 3 × 10¹² m/s
Correct answer: 3 × 10⁸ m/s
The speed of light in vacuum (c) is approximately 3 × 10⁸ m/s (exactly 299,792,458 m/s). This is a fundamental constant of nature.
The speed of light in vacuum (denoted 'c') is exactly 299,792,458 m/s ≈ 3 × 10⁸ m/s. This is a fundamental physical constant. Light travels approximately 300,000 km per second. Key facts: Light takes about 8 minutes 20 seconds to travel from Sun to Earth (about 150 million km); Light from the Moon reaches Earth in 1.3 seconds; Light from the nearest star (Proxima Centauri) takes about 4.2 years — hence the concept of a 'light year' as a unit of distance (9.46 × 10¹² km). According to Einstein's Special Theory of Relativity, no object with mass can travel at or beyond the speed of light.
Question 4: Which vitamin is produced by the human body when exposed to sunlight?
- Vitamin A
- Vitamin B12
- Vitamin C
- Vitamin D (Correct answer)
Correct answer: Vitamin D
Vitamin D (also called the 'sunshine vitamin') is synthesized in the skin when exposed to UVB rays from sunlight through a process involving 7-dehydrocholesterol.
Vitamin D is the only vitamin that can be synthesized by the human body. When skin is exposed to UVB (ultraviolet B) radiation from sunlight, 7-dehydrocholesterol in the skin is converted to Vitamin D3 (cholecalciferol). Vitamin D is crucial for: calcium and phosphorus absorption, bone formation, immune function, and muscle function. Deficiency causes rickets (in children) and osteomalacia (in adults). Other fat-soluble vitamins (A, E, K) cannot be synthesized by the body. Vitamin B12 is produced by bacteria and found in animal products. Vitamin C (ascorbic acid) must be obtained from diet — its deficiency causes scurvy.
Question 5: Newton's First Law of Motion is also known as the Law of:
- Gravitation
- Acceleration
- Inertia (Correct answer)
- Action-Reaction
Correct answer: Inertia
Newton's First Law of Motion is called the Law of Inertia: an object at rest stays at rest, and an object in motion stays in motion unless acted upon by an external force.
Newton's Three Laws of Motion: First Law (Law of Inertia): An object remains at rest or in uniform motion in a straight line unless acted upon by a net external force. Inertia is the resistance of an object to change in its state of motion, proportional to its mass. Second Law (Law of Acceleration/Force): F = ma. Force equals mass times acceleration. Third Law (Law of Action-Reaction): For every action, there is an equal and opposite reaction. These laws were published in 'Principia Mathematica' (1687). Examples of First Law: Passengers jolted forward when a bus brakes suddenly; Dust falling off a rug when shaken; A ball rolling on a smooth surface continues until friction stops it.
Question 6: DNA stands for:
- Deoxyribose Nucleic Acid
- Deoxyribonucleic Acid (Correct answer)
- Double-helix Nucleic Acid
- Dioxynucleic Acid
Correct answer: Deoxyribonucleic Acid
DNA stands for Deoxyribonucleic Acid. It is the hereditary material in all known organisms and most viruses.
DNA (Deoxyribonucleic Acid) is a double-helix shaped molecule that carries genetic information in all living organisms and most viruses. The structure of DNA was first described by James Watson and Francis Crick in 1953 (based on Rosalind Franklin's X-ray crystallography work). DNA is made up of nucleotides, each containing: a deoxyribose sugar, a phosphate group, and a nitrogenous base (Adenine, Thymine, Guanine, or Cytosine). Complementary base pairs: A-T and G-C. In contrast, RNA (Ribonucleic Acid) uses ribose sugar and Uracil instead of Thymine. DNA is found in the nucleus, mitochondria, and chloroplasts of eukaryotic cells.
RRB NTPC Science and Technology Basics 1
Which instrument is used to measure atmospheric pressure?