Chemistry MCQs

Notes:
The primary component for electric vehicle batteries is Lithium, used as Lithium carbonate or Lithium hydroxide. These Lithium-ion batteries have a high power-to-weight ratio, energy efficiency, and thermal stability, leading to their prevalence in electric vehicles. Notably, the boom in EVs has significantly driven the demand for Lithium globally.

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:
A cotton wick soaked in pure honey, when lit with a matchstick, will burn consistently. This is primarily due to the high sugar content of the honey acting as fuel for the flame. Contrary to common misconceptions, honey doesn’t produce much smoke or any unusual sounds during combustion.

Notes:
Adsorption, the binding of gas or liquid particles to a solid surface, is often used in chromatography – a laboratory technique for the separation of a mixture. This process is critical as it allows the separation of the compounds in the mixture, thereby enabling further analysis or purification. Apart from chromatography, adsorption is also used in scrubbers and purification of solids and liquids.

Notes:
The correct answer is Hydrochloric Acid. When testing for adulteration of pure ghee with vanaspati or margarine, hydrochloric acid is used because it reacts with the fats present in these substances, producing a distinct color change. This method is based on the principle that the presence of unsaturated fats in vanaspati or margarine will lead to a different reaction compared to pure ghee. Hydrochloric acid is commonly used in food testing due to its effectiveness in identifying such adulterants.

Notes:
“Butter of Tin” is also known as tin tetrachloride pentahydrate. It is called “butter of tin” because of its physical appearance. Its chemical formula is SnCl4*5H2O or [SnCl4 (H2O)]*3H2O.

Notes:
The funda is that when a small drop of a strong acid, such as nitric acid, is put onto the metal’s surface, most metals fizz or bubble, whilst precious metals (Gold or Platinum not silver) are unaffected.

Notes:
Crystallisation is a process that separates a pure solid in the form of its crystals from a solution. For example: purification of the salt obtained from sea water.

Notes:
Sphalerite (ZnS) is a sulphide. All others are oxides. Haematite and Magnetite are the oxides of iron and Cuprite is an oxide of Copper.

Notes:
Leaching is used for ore concentration if the ore is soluble in some suitable solvent. For example: Leaching of alumina from bauxite using conc. NaOH.