Chemistry MCQs

Notes:
Acid rain is caused by nitrous oxides (NOx) and sulfur dioxide (SO2) emissions, which react with water molecules in the atmosphere to form nitric and sulfuric acids. These acids then fall to the ground in rain, snow, fog, or dust particles.

Notes:
The correct answer is John Dalton. He proposed the Atomic Theory in the early 19th century, stating that matter is composed of indivisible atoms, each with a specific weight. Dalton’s work laid the foundation for modern chemistry. Notably, he also introduced the concept of atomic weights and was the first to use symbols to represent atoms of different elements.

Notes:
Oxidation is a chemical reaction in which an atom, ion, or molecule loses an electron to another substance. So, the correct answer is “Electrons are lost”. This phenomenon is often observed in various chemical and biological systems. Understanding this important process can allow us to gain insights in fields ranging from biology to materials science.

Notes:
Graphite is renowned for its conspicuous uses owing to its unique properties like its ability to conduct electricity, which makes it ideal for electrode manufacturing. It’s also used as a lubricant and in the production of crucibles, thanks to its high melting point. However, it isn’t used in glass cutting.

Notes:
Sodium Alkyl Sulphate and Benzene Sulphate are typical examples of Synthetic Detergents. Synthetic detergents are man-made cleansing agents that function similarly to soap. These compounds were developed during World War II when a shortage of natural oils led to a search of alternative substances. The advanced features of synthetic detergents include improved cleansing efficacy, resistance to water hardness, and the ability to function in acidic conditions.

Notes:
The correct answer is Helium. Helium is a non-flammable, lighter-than-air gas, making it safe for use in balloons. Unlike hydrogen, which is highly flammable and poses explosion risks, helium is inert and does not react with other substances. Helium is the second most abundant element in the universe, primarily produced through nuclear fusion in stars. It was first discovered in the sun before being found on Earth.

Notes:
Under standard conditions, Graphite is the most stable form of carbon. It is commonly used in pencils and lubricants due to its layered structure. These layers can move over each other, making graphite soft and slippery. Besides Graphite, other forms of carbon are diamond, charcoal, and amorphous carbon, each with unique properties and applications.

Notes:
Pyrolusite, Braunite, Psilomelane, and Rhodochrosite are all ores of Manganese. Pyrolusite is one of the most important ores due to its high manganese content. Braunite, although a significant ore, its manganese content is less than Pyrolusite. Psilomelane and Rhodochrosite also contribute as minor ores.

Notes:
Pure diamond should transmit visible light and appear as a clear colorless crystal. Colors in diamond originate from lattice defects and impurities. The diamond crystal lattice is exceptionally strong and only atoms of nitrogen, boron and hydrogen can be introduced into diamond during the growth at significant concentrations (up to atomic percents). Nitrogen gives yellowish color while the Boron gives bluish color.

Notes:
Buna-S is a synthetic rubber formed by co-polymerization of a mixture of 1:3 butadiene and styrene. It is obtained from Sodium.