Chemistry MCQs

Notes:
The noble gases are the chemical elements in group 18 of the periodic table. They are the most stable due to having the maximum number of valence electrons their outer shell can hold. This chemical series contains helium, neon, argon, krypton, xenon, and radon.

Notes:
MTBE is a gasoline additive, used as an oxygenate to raise the octane number. Its use is controversial in the US and declining in that country in part because of its occurrence in groundwater and legislation favoring ethanol.

Notes:
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).

Notes:
Calamine is an ore that contains zinc carbonate along with impurities like iron oxide. Through smelting, the zinc carbonate in calamine can be reduced to extract pure zinc metal. Other common zinc ores are sphalerite (zinc sulfide) and smithsonite (zinc carbonate). So calamine is considered a zinc ore due to its zinc carbonate content.

Notes:
The correct statement is that in an alkaline battery, the negative terminal is made of zinc powder, the positive terminal is made of manganese dioxide, and the electrolyte is potassium hydroxide (KOH). Alkaline batteries are known for their long shelf life and higher energy density compared to zinc-carbon batteries. They were invented in the 1950s and are widely used in household devices.

Notes:
The correct answer is 2. The lanthanides are a series of 15 elements in the periodic table, from atomic numbers 57 (Lanthanum) to 71 (Lutetium). They are known for their similar properties and are often found together in nature. The range of atomic numbers for lanthanides is 57 to 71, not 57-70 or 58-70.

Notes:
Alkaloids are a class of naturally occurring organic compounds that mostly contain basic nitrogen atoms. Nitrogen is essential in their structure, contributing to their pharmacological properties. Common examples of alkaloids include morphine, caffeine, and nicotine, all of which contain nitrogen. Sodium, magnesium, and potassium are not fundamental components of alkaloids.

Notes:
The Carbon Group of the periodic table includes the elements carbon, silicon, germanium, tin, lead, and flerovium. These elements have four electrons in the outermost shell. Selenium, however, is not a part of this group. It is a member of the Chalcogens and sits beneath Oxygen in the periodic table. The element number for Selenium is 34. It is known for its photovoltaic and photocatalytic properties.

Notes:
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.

Notes:
Flint is a sedimentary rock. It’s a type of microcrystalline quartz in the chert family. Flint is known for its sharp edges and ability to be easily flaked into various shapes. It was widely used by early humans to make a variety of tools, including:  Knives, Scrapers, Points, Axe-heads, Hammers, Choppers. Flint is often found along streams and beaches. It’s close behind diamond in hardness and fractures easily to give razor sharp edges.