Chemistry MCQs

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Fluorine is most active because it has the highest electronegativity.

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Sodium thiosulfate is an important inorganic salt with several medical uses. It is also called sodium hyposulfite or ‘hypo’. It is used in several pharmaceutical preparations and also has various medical properties. 

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Radium(Ra) with atomic number 88 was discovered by Marie and Pierre Curie in 1898 as Radium Chloride. However, it was Radium was isolated in its metallic state by Marie Curie and André-Louis Debierne through the electrolysis of radium chloride in 1911.

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The given principle is one of the postulates of the Dalton’s atomic theory given in 1803 by John Dalton. The postulates of Dalton’s atomic theory are as follows: 
1. Elements consist of indivisible small particles (atoms). 
2. All atoms of the same element are identical; different elements have different types of atom. 
3. Atoms can neither be created nor destroyed. 
4. ‘Compound elements’ (i.e. Compounds) are formed when atoms of different elements join in simple ratios to form ‘compound atoms’ (i.e. Molecules).

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The reaction of alkali metals with water produces Hydrogen gas. These metals are part of the first group on the period table and include lithium, sodium, and potassium. They are known for their vigorous reactions with water, which results in the liberation of hydrogen gas. Along with the gas, this reaction also forms a basic alkali metal hydroxide, which gives the solution its characteristic basic or alkaline properties.

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The Haber Process is an industrial method for synthesizing ammonia from nitrogen and hydrogen gases. Developed by Fritz Haber and Carl Bosch in the early 20th century, it operates under high pressure and temperature, using an iron catalyst. Ammonia produced is crucial for fertilizers, supporting global agriculture. The process importantly increased food production, earning Haber the Nobel Prize in Chemistry in 1918.

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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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The correct answer is Mercury. An amalgam is a specific type of alloy that primarily consists of mercury mixed with another metal, commonly used in dental fillings due to its durability and ease of use. Historically, amalgams have been used since ancient times, with the earliest known use dating back to the 9th century in China.

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Hydrogen chloride gas released from volcanic eruption is responsible for temporary acid rain in colder regions.

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Calcium carbonate is used as a building material in the form of marble and in the manufacture of quick lime. Calcium carbonate is also used in the manufacture of high quality paper. It finds its use as an antacid, mild abrasive in tooth paste, a constituent of chewing gum, and a filler in cosmetics.