Chemistry MCQs

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The agricultural industry widely uses urea, a white crystalline solid containing 46 percent nitrogen as an animal feed additive and fertilizer. Urea has the highest nitrogen content of all solid fertilizers at 46% N.

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Brass is an alloy of Copper and Zinc, in proportions which can be varied to achieve varying mechanical and electrical properties. The proportions of Zinc and Copper can vary to create different types of brass alloys with varying mechanical and electrical properties.

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Sodium sulfate, used as a filler in detergent powder, enables the adjustment of the concentration of the active matter in the detergent, as required.

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Cellulose is the most abundant organic compound in nature. It is the main constituent of plant fiber. Plants contain on average 33% cellulose, and cotton is the purest form at 90%. Chitin is the second most abundant organic compound in nature.

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Phenolphthalein is commonly employed as a pH indicator in titrations due to its distinct color change in varying pH levels. At pH 8.2, it appears colorless but turns pink as the pH increases to 10. It is not used as a solvent, catalyst or detergent. It also finds applications in forensic science for detecting latent blood stains.

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Helium atoms that have lost two electrons are called alpha rays. Alpha rays are also called alpha particles or alpha radiation. Alpha particles are made up of two protons and two neutrons bound together into a particle that is identical to a helium-4 nucleus.
Alpha particles are named after the first letter in the Greek alphabet, α. They were the first nuclear radiation to be discovered.
When a helium atom loses its electrons, it is left with only the nucleus. This is called an alpha particle.

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When Mendeleev published his periodic table in 1869, noble gases had not yet been discovered. The first noble gas, argon, was identified in 1894 by Lord Rayleigh and William Ramsay. In contrast, lanthanides and actinides were recognized later, but their existence was inferred from Mendeleev’s predictions. Halogens, including elements like chlorine and iodine, were known prior to Mendeleev’s work.

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Aluminum is considered a “Green Metal” primarily due to its high recycling rate. Approximately 75% of all aluminum ever produced is still in use today, as it can be recycled indefinitely without losing quality. This process saves energy—recycling aluminum uses about 95% less energy than producing new aluminum from bauxite ore. Additionally, recycling reduces greenhouse gas emissions and conserves natural resources, making aluminum a sustainable choice in various applications.

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Potassium graphite and calcium graphite are primarily used as superconductors. Superconductors are materials that can conduct electricity without resistance when cooled below a certain temperature. Graphite, particularly when doped with potassium or calcium, exhibits enhanced superconducting properties. Notably, the discovery of high-temperature superconductors in the 1980s revolutionized the field, leading to applications in magnetic levitation and advanced electronic devices.

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Ozone (O3) is the most common photochemical oxidant in photochemical smog. Inhaling ozone can cause irritation to the mucous membrane and respiratory system. Ozone can also cause chest constriction and damage to vegetation.

Other components of photochemical smog include:

• Nitrogen dioxide (NO2)
• Peroxyacetylnitrate (PAN)
• Aldehydes

Other air pollutants that can be harmful to humans include:

• Sulfur dioxide
• Volatile organic compounds (VOCs)
• Dioxins
• Polycyclic aromatic hydrocarbons (PAHs)

Carbon monoxide can cause hyperventilation, respiratory distress, and stillbirths. At high levels, carbon monoxide can even cause direct poisoning.