Chemistry MCQs

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:
Zinc sulfate is the inorganic compound with the formula ZnSO4 and historically known as “white vitriol” Zinc sulfate is an inorganic compound and dietary supplement.

Notes:
Sodium benzoate is commonly used as a preservative in food and beverages, including tomato juice. It inhibits the growth of mold, yeast, and some bacteria, extending shelf life. It is effective in acidic environments, such as those found in tomato products, where the pH is typically below 4.6. Sodium chloride (salt) can also act as a preservative but is primarily used for flavor. Sodium carbonate and sodium lauryl sulfate are not suitable preservatives for tomato juice.

Notes:
The main constituent of vegetable oil and animal fats is triglyceride. Triglycerides are composed of three fatty acids linked to a glycerol molecule. They are the most common type of fat found in the body and serve as a major energy source. In fact, triglycerides account for about 95% of the fats in the human diet.

Notes:
The first synthetic plastic was actually celluloid, invented by Alexander Parkes in 1855. Initially, celluloid was primarily used in photographic films. However, it had limitations, not suitable for making containers or electrical insulation. The first genuine plastic, Bakelite, was invented by Leo Baekeland in 1909 and extensively used in various applications, including safely handled autos. World War I significantly contributed to the development of polystyrene and polyvinyl chloride, widely used in plumbing and electrical insulation. Later, in the 1930s, nylon was invented, and by 1950, plastic materials gained immense popularity.

Notes:
The correct answer is Chlorine. – Gammaxene (also known as Lindane) is a pesticide derived from hexachlorocyclohexane, which involves chlorine. – D.D.T. (Dichloro-Diphenyl-Trichloroethane) is a synthetic pesticide containing chlorine. – Bleaching powder (calcium hypochlorite) is a chlorine compound used for disinfection and bleaching. Chlorine is essential in various chemical processes and compounds, particularly in agriculture and sanitation.

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.

Notes:
Helium has the lowest boiling point of all the elements at –452.074°F (–268.93°C) followed by hydrogen –423.16°F (–252.87°C). The highest boiling point for an element is that of Rhenium 10,104.8°F (5,596°C) followed by tungsten 10,031°F (5,555°C).

Notes:
Methanol, CH₃OH, also known as ‘wood spirit’. It was produced by destructive distillation of wood.

Notes:
Centrifugation is a mechanical process that utilizes an applied centrifugal force field to separate the components of a mixture.