Question 1

The chemical formula of Laughing Gas is:

Accepted Answer

Correct Answer: N2O

Explanation: Laughing Gas is Nitrous Oxide (N2O). It is a colorless gas with a sweet smell used in surgery and dentistry for its anaesthetic and analgesic effects. Inhaling it produces a euphoric state, sometimes leading to laughter. It is also used as an oxidizer in rocket engines and to increase power in racing cars.

Question 2

Which device is used to measure current?

Accepted Answer

Correct Answer: Ammeter

Explanation: An Ammeter is used to measure the magnitude of electric current in a circuit. It is always connected in series with the component being measured so that the entire current flows through it. It has very low resistance to avoid affecting the circuit's operation. The unit of measurement is the Ampere (A).

Question 3

The filament of an electric bulb is made of:

Accepted Answer

Correct Answer: Tungsten

Explanation: Tungsten is used for bulb filaments because it has the highest melting point of all metals (3422°C). This allows it to become white-hot and emit light without melting. It also has high resistance. The bulb is filled with inert gas (argon) to prevent the tungsten from burning up in the presence of oxygen.

Question 4

Which is the lightest gas?

Accepted Answer

Correct Answer: Hydrogen

Explanation: Hydrogen (H2) is the lightest and most abundant element in the universe. However, on Earth, it is rarely found in its pure gaseous form because it escapes gravity easily. Helium is the second lightest. Although hydrogen is lighter, balloons often use helium because hydrogen is highly flammable and dangerous.

Question 5

Which Vitamin aids in the clotting of blood?

Accepted Answer

Correct Answer: Vitamin K

Explanation: Vitamin K is essential for the synthesis of proteins required for blood coagulation (clotting). Without it, even minor injuries could lead to uncontrollable bleeding. It is naturally found in green leafy vegetables like spinach and kale, and is also produced by beneficial bacteria in the human intestine.

Question 6

The image formed on the Retina of the human eye is:

Accepted Answer

Correct Answer: Real and Inverted

Explanation: The lens of the eye acts like a convex lens, focusing light onto the retina. The image formed is Real and Inverted (upside down). However, the optic nerve transmits this signal to the brain, which processes the information and flips the image, allowing us to perceive the world as upright.

Question 7

Which acid is used in Car Batteries?

Accepted Answer

Correct Answer: Sulfuric Acid

Explanation: Lead-acid car batteries use diluted Sulfuric Acid (H2SO4) as the electrolyte. It allows the flow of electrons between the lead plates, generating electricity to start the engine and power electronics. It is a highly corrosive strong acid. The battery works by converting chemical energy into electrical energy and is rechargeable.

Question 8

What is the main constituent of Gobar Gas?

Accepted Answer

Correct Answer: Methane

Explanation: Gobar Gas (Biogas) is primarily composed of Methane (CH4), which makes up 50-75% of the mixture. It is produced by the anaerobic decomposition of organic matter like cattle dung (gobar) and agricultural waste. It is a clean, renewable fuel used for cooking and lighting in rural areas, and the residue makes excellent organic fertilizer.

Question 9

Which part of the eye is donated in Eye Donation?

Accepted Answer

Correct Answer: Cornea

Explanation: In eye donation, only the Cornea is transplanted, not the whole eye. The cornea is the clear, transparent front layer of the eye. Corneal blindness affects millions, and a transplant can restore vision. Since the cornea has no blood supply (it gets oxygen from the air), rejection rates are lower than organ transplants.

Question 10

Who discovered the Electron?

Accepted Answer

Correct Answer: J.J. Thomson

Explanation: J.J. Thomson, a British physicist, discovered the electron in 1897 through his cathode ray tube experiments. He showed that cathode rays were composed of negatively charged particles much smaller than atoms. This discovery revolutionized the understanding of atomic structure, leading to the 'Plum Pudding Model' of the atom.

Question 11

Which gas is evolved during respiration?

Accepted Answer

Correct Answer: Carbon Dioxide

Explanation: During respiration, animals and humans inhale oxygen and exhale Carbon Dioxide (CO2). Cells use oxygen to break down glucose for energy (cellular respiration), and CO2 is produced as a waste product. This CO2 travels in the blood to the lungs, where it is breathed out. Plants do the reverse during the day (photosynthesis).

Question 12

Deficiency of Iron causes:

Accepted Answer

Correct Answer: Anemia

Explanation: Iron deficiency causes Anemia, specifically Iron Deficiency Anemia. Iron is a key component of hemoglobin, which carries oxygen in the blood. Without enough iron, the body can't produce enough healthy red blood cells, leading to fatigue, weakness, pale skin, and shortness of breath. It is the most common nutritional deficiency worldwide.

Question 13

Which metal is liquid at room temperature?

Accepted Answer

Correct Answer: Mercury

Explanation: Mercury (Symbol: Hg) is the only metal that is liquid at standard room temperature and pressure. It is a heavy, silvery-white metal. Due to its unique properties, it is used in thermometers, barometers, and manometers. However, it is highly toxic and can cause severe damage to the nervous system if inhaled or ingested.

Question 14

What is the speed of sound in air?

Accepted Answer

Correct Answer: 332 m/s

Explanation: The speed of sound in dry air at 0°C is approximately 332 meters per second. The speed increases as the temperature rises (about 343 m/s at 20°C). Sound travels as a longitudinal wave. It is much slower than the speed of light, which is why we see lightning before we hear the thunder.

Question 15

Which gland regulates the blood sugar level?

Accepted Answer

Correct Answer: Pancreas

Explanation: The Pancreas regulates blood sugar levels by producing two main hormones: Insulin and Glucagon. Insulin lowers blood sugar by helping cells absorb glucose, while Glucagon raises blood sugar by releasing stored glucose from the liver. An imbalance in these hormones leads to Diabetes Mellitus.

Question 16

Which disease is caused by the bite of a mad dog?

Accepted Answer

Correct Answer: Rabies (Hydrophobia)

Explanation: Rabies is a deadly viral disease transmitted through the saliva of infected animals, usually dogs (also bats and raccoons). It attacks the central nervous system. A classic symptom is Hydrophobia (fear of water) due to painful throat spasms when trying to swallow. Once symptoms appear, it is almost always fatal, so immediate vaccination is crucial.

Question 17

The chemical name of Bleaching Powder is:

Accepted Answer

Correct Answer: Calcium Hypochlorite

Explanation: Bleaching Powder is chemically Calcium Hypochlorite [Ca(ClO)2]. It is a white powder with a strong smell of chlorine. It is used for disinfecting drinking water and for bleaching cotton and linen in the textile industry. It releases chlorine when it reacts with dilute acids, which acts as the bleaching agent.

Question 18

Which instrument is used to measure the depth of the ocean?

Accepted Answer

Correct Answer: Fathometer (Sonar)

Explanation: A Fathometer, which uses SONAR (Sound Navigation and Ranging) technology, is used to measure ocean depth. It sends sound waves down to the ocean floor and measures the time it takes for the echo to return. Knowing the speed of sound in water, the distance (depth) can be calculated accurately.

Question 19

What is the unit of pressure?

Accepted Answer

Correct Answer: Pascal

Explanation: The SI unit of pressure is the Pascal (Pa). One Pascal is defined as one Newton of force applied over an area of one square meter. It is named after Blaise Pascal, a French mathematician. Weather reports often use kilopascals (kPa) or millibars to measure atmospheric pressure.

Question 20

Which planet is known as the 'Red Planet'?

Accepted Answer

Correct Answer: Mars

Explanation: Mars is called the Red Planet because its surface is covered with iron oxide (rust) dust, giving it a reddish appearance. It is the fourth planet from the Sun. It has the largest volcano (Olympus Mons) and the deepest canyon (Valles Marineris) in the solar system. Scientists are exploring it for signs of past life.

Everyday Science MCQs