Chemistry MCQs

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The most important form of elemental phosphorus from the perspective of applications and chemical literature is white phosphorus. It consists of tetrahedral P4 molecules, in which each atom is bound to the other three atoms by a single bond. This P4 tetrahedron is also present in liquid and gaseous phosphorus up to the temperature of 800 °C when it starts decomposing to P2 molecules

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Water at 4 degrees Celsius has maximum density. This is due to the unique molecular structure of water, which allows it to reach its highest density at this temperature. As water cools from higher temperatures, it becomes denser until it reaches 4 degrees. below this temperature, it begins to expand, making ice less dense than liquid water. This phenomenon is crucial for aquatic life, as it allows ice to float, insulating the water below.

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Cobalt Oxide is commonly used to create a distinctive blue hue in glasses and ceramics. The depth of the blue can be altered by changing the concentration of the oxide. In addition to being used for aesthetic purposes, Cobalt blue, which results from Cobalt Oxide, is also used because it absorbs certain wavelengths of light, making it useful for filtering out unwanted wavelengths.

Notes:
Chlorine has an atomic number of 17, meaning it has 17 protons. Its atomic weight is approximately 35, which indicates it typically has 18 neutrons (35 – 17 = 18). Therefore, the correct composition is 17 protons and 18 neutrons. Chlorine is a halogen and exists primarily as two stable isotopes: Chlorine-35 and Chlorine-37.

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The main constituent of vegetable oil and animal fats is triglyceride. Triglycerides are composed of three fatty acids linked to a glycerol molecule. They are the most common type of fat found in the body and serve as a major energy source. In fact, triglycerides account for about 95% of the fats in the human diet.

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Strontium-90 is a “bone seeker” that exhibits biochemical behaviour similar to calcium, the next lighter Group 2 element. After entering the organism, most often by ingestion with contaminated food or water, about 70–80% of the dose gets excreted. Virtually all remaining strontium-90 is deposited in bones and bone marrow, with the remaining 1% remaining in blood and soft tissues. Its presence in bones can cause bone cancer, cancer of nearby tissues, and leukaemia.

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The high-quality (100% Pure) Syngas has the main components of (H2 + CO)

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In India, the Double Sulphitation is the most commonly used method for refining of sugar. Also, it is the cheapest process of refining sugar as compared to other available process.

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Diethyl ether is a colourless, highly volatile & flammable organic compound. It was earlier used for anaesthesia but after the development of non-flammable drugs, its uses as anaesthetic has been reduced.

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If the rust stays attached to the main body or the flakes of rust that fall off are collected and weighed than the weight will increase. If you are using for example iron shavings than the chemical formula would look like this Fe(II) + O2 = FeO2 And the weight will increase by the mass of the shavings divided by the molar mass of iron times 2 times the molar mass of oxygen (in this case taking the molar mass of oxygen as a single oxygen atom not a pair). Thus, When rust forms, the mass of the iron object is increased by the mass of oxygen that has combined with some of the iron