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The correct answer is CaCO₃.

Key Points

• Lime water is calcium hydroxide and when carbon dioxide is passed it reacts with calcium hydroxide to form calcium carbonate which turns lime water milky.
• Lime manufacture
• From the earliest of times, lime has been made by heating limestone to high temperatures.
• Production methods have evolved from heating limestone in open fires, to the use of brick lime kilns at the start of the 17^th century, to today’s horizontal rotating kilns several metres in diameter and up to 100 metres in length.
• These modern kilns operate at a temperature of about 1100-1200°C, allowing rapid conversion of limestone into lime.
• CaCO3(s) limestone → CaO(s) lime + CO2(g) carbon dioxide
• Lime’s chemical properties
• Lime (calcium oxide) is a white solid with strongly basic properties.
• The lime reacts readily with water to produce slaked lime, which is the chemical compound calcium hydroxide. A considerable amount of heat energy is released during this reaction.
• CO2 is a colourless, odourless, incombustible gas. It is a product of cellular respiration and combustion and is an essential component in photosynthesis.

The correct answer is Option 4.

Key Points

• The haemoglobin in our blood takes oxygen to different parts of our body from the Lungs.
• The oxygen affinity of haemoglobin. is less than that of  CO affinity towards haemoglobin.
• When we inhale air polluted with carbon monoxide (CO), carbon monoxide (CO) will combine with haemoglobin, forming carboxyhemoglobin in the blood and Stopping oxygen transport.
• The binding of carbon monoxide to haemoglobin, forming carboxyhemoglobin, reduces the amount of oxygen available to the heart muscle and other tissues for synthesizing ATP.
• It is a pollutant for humans since it reacts with Haemoglobin. It is harmful when breathed since it displaces oxygen in the blood and deprives the heart, brain and other important organs.

The correct answer is Virus.

Key Points 

• The - cell - theory notes that all living things are made up of cells, cells are the fundamental units of living things' structure and function and all cells come from other cells.
• Since viruses do not consist of cells and do not use cells in any of their processes, they are not related to the theory of cells.

Additional Information 

• Antonie van Leeuwenhoek discovered bacteria from the human mouth in 1683.
• Two scientists contributed to the discovery of the first virus, Tobacco mosaic virus. Ivanoski reported in 1892 that extracts from infected leaves were still infectious after filtration through a Chamberland filter-candle.

The correct answer is Option 4.

Key Points

• On a clean glass plate a drop of water spreads to form a thin layer whereas a drop of mercury remains almost spherical because cohesion of mercury is greater than its adhesion with glass.
• The cohesive force is the force of attraction that exists between molecules of the same substance. As opposed to this, a force known as non-cohesive force acts between molecules of various substances. When put within a container, substances whose cohesive force acting between the molecules is stronger than the non-cohesive force won't adhere to the walls of the vessel.
• Mercury droplets on a glass plate, for instance, continue to be circular. However, those liquids wet the surface of the vessel when the cohesive force operating between the molecules of a liquid is less than the cohesive force acting between the liquid and the vessel.

The correct answer is Hygrometer.

Key Points

• 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 hygrometer
• Mechanical hygrometer
• What is Humidity?
• Humidity is the amount of water vapor in the atmosphere caused by condensation and evaporation.
• It can be measured as absolute humidity or relative humidity.

Additional Information

• A thermometer is a medical device that helps to measure the temperature, which is the temperature of the heart, brain, and other organs.

The correct answer is Malaria.

Key Points

• Plasmodium is a genus of parasitic protozoa that is responsible for causing malaria, a serious and potentially life-threatening disease.
• Malaria is primarily transmitted through the bite of infected female Anopheles mosquitoes.
• When an infected mosquito bites a human, it injects Plasmodium parasites into the bloodstream.
• Once inside the human body, the Plasmodium parasites travel to the liver and multiply.
• They then infect and destroy red blood cells, leading to the characteristic symptoms of malaria.
• These symptoms can include high fever, chills, sweating, headache, muscle aches, fatigue, nausea, and vomiting.
• There are several species of Plasmodium that can infect humans, including P. falciparum, P. vivax, P. malariae, and P. ovale.
• Among these, P. falciparum is the most severe and can lead to life-threatening complications, particularly in young children and individuals with weakened immune systems.

Additional Information

• Common cold: The common cold is primarily caused by various types of viruses, most commonly rhinoviruses. Other viruses that can cause the common cold include coronaviruses, respiratory syncytial virus (RSV), adenoviruses, and parainfluenza viruses.
• Typhoid: Typhoid fever is caused by the bacterium Salmonella enterica serovar Typhi. It is typically contracted by consuming food or water contaminated with feces containing the bacterium. Poor sanitation and hygiene practices contribute to its spread.
• Pneumonia: Pneumonia can have various causes, including bacterial, viral, or fungal infections. The most common cause of bacterial pneumonia is Streptococcus pneumoniae. Viral pneumonia can be caused by influenza viruses, respiratory syncytial virus (RSV), adenoviruses, and others. Fungal pneumonia is often associated with specific fungi, such as Pneumocystis jirovecii in immunocompromised individuals.

The correct answer is Vitamin B and Vitamin C.

Key Points

• Vitamins are nutrients your body needs to develop and function properly.
• There are 13 essential vitamins: A, D, E, and K, which are fat-soluble, and vitamins C and the B-complex group, which are water-soluble.
• Each vitamin has a distinct role in keeping you healthy.

Important Points

Trick to remember fat-soluble vitamins- KEDA

• K-Vitamin K
• E- vitamin E
• D-vitamin D
• A-vitamin A

The correct answer of above Question is option 1. 

Key Points

• Brushing teeth regularly has numerous benefits, but it does not directly contribute to strengthening the muscles of our body.
• The main advantages of regular brushing include protecting our gums, reducing/preventing bad breath, and removing food particles stuck in our teeth.
• However, muscle strength is typically developed through physical exercise, strength training, and proper nutrition.
• Regular brushing helps maintain oral hygiene, prevents tooth decay, reduces the risk of gum disease, and promotes overall dental health.
• It also aids in maintaining fresh breath and a clean mouth.
• While brushing is an essential part of oral care, it does not have a direct impact on muscle strength or development in the body.

The correct answer is because ​it contains acetic acid.

Key Points

• Vinegar is used to preserve food primarily because it contains acetic acid.
• Acetic acid is a weak acid that acts as a natural preservative by creating an acidic environment that inhibits the growth of bacteria, mold, and other microorganisms that cause food spoilage.
• The acetic acid in vinegar helps to lower the pH of the food, making it less hospitable for bacteria to thrive.
• This preservation process helps extend the shelf life of food by slowing down the spoilage process.
• It is worth noting that vinegar does not contain hydrochloric acid, sulfuric acid, or fluoridic acid, and these acids are not typically used for food preservation purposes.

The correct answer is Saffron.

Key Points

• Saffron is a spice derived from the flower of Crocus sativus, commonly known as the “saffron crocus.”
• Saffron contains several plant-derived chemical compounds that are known to have been antioxidant, disease-preventing, and health-promoting properties.
• It is also used as an insecticide or pesticide.
• The scientific name of "Turmeric" is Curcuma longa.
• The scientific name of "Artichoke" is Cynara scolymus.
• The scientific name of "Ginger" is Zingiber officinale.