The correct answer is option 1 i.e. Thomas Andrews.

In the 1860s, physicist Thomas Andrews undertook a thorough investigation of the gas laws, focusing on the relationships of pressure, temperature, and volume in carbon dioxide. His work led to the discovery of the critical point, where the distinct boundaries between liquid and gas phases disappear. Andrews' experiments and findings were significant in understanding the behavior of gases and contributed to the development of thermodynamics and physical chemistry.

The correct answer is option 4 i.e. Dirac equation.

In 1928, Paul Dirac derived the Dirac equation, which combines quantum theory and special relativity to describe the behavior of an electron moving at relativistic speeds. The Dirac equation accounts for the relativistic effects and predicts the existence of antimatter. It successfully merges the principles of quantum mechanics with special relativity, providing a more accurate description of electron behavior and leading to significant advancements in quantum field theory and particle physics.

The correct answer is option 4 i.e. Carl Anderson.

In 1932, the positron was discovered by physicist Carl Anderson. He observed this particle, which carries a positive charge and has a mass equivalent to that of a free negative electron, while studying cosmic rays using a cloud chamber. Anderson’s discovery provided crucial evidence for the existence of antimatter and confirmed the theoretical prediction made by Paul Dirac. For this groundbreaking work, Anderson was awarded the Nobel Prize in Physics in 1936.

The correct answer is option 2 i.e. Resorcinol.

The 1,3-isomer (or meta-isomer) of benzenediol with the chemical formula C₆H₄(OH)₂ is Resorcinol. Resorcinol features two hydroxyl groups (-OH) attached to the benzene ring at the meta positions relative to each other. It is distinct from catechol (1,2-isomer) and m-cresol (1,3-isomer of toluene), and glycerol is not a benzenediol but a trihydroxy alcohol.

The correct answer is option 2 i.e. Dry ice.

Solid carbon dioxide is commonly known as dry ice. It is called dry ice because, unlike regular ice, it does not melt into a liquid form but sublimates directly into carbon dioxide gas at temperatures above −78.5°C (−109.3°F). Dry ice is used for cooling purposes, in theatrical effects to create fog, and in various industrial applications due to its ability to maintain very low temperatures without leaving any residue.

The correct answer is option 2 i.e. gaining.

Non-metals are electronegative, meaning they have a tendency to attract electrons towards themselves. They tend to form bonds by gaining electrons. This is because non-metals typically have a higher affinity for electrons and require additional electrons to complete their valence shells, achieving a stable electronic configuration. This property is what leads to the formation of anions (negatively charged ions) when non-metals participate in chemical bonding.

The correct answer is option 3 i.e. Potassium meta bisulphite.

Potassium metabisulphite is a chemical compound used as a food preservative and additive that helps maintain the natural color of food and prevents bacteria growth. 

Other chemical compounds used as food preservatives include:

Sodium benzoate

Sodium metabisulphite

Butylated hydroxyanisole

Benzoic acid

The correct answer is option 3 i.e. Edward Davies Hughes.

• In 1937, British chemist Sir Christopher Ingold and Edward Davies Hughes proposed a mechanism for the SN2 reaction, which explains the inversion of configuration and second-order kinetics observed in nucleophilic substitution reaction. 
• SN2 stands for substitution, nucleophilic, bimolecular, which means that two molecules, the nucleophile and the alkyl halide, take part in the step whose kinetics are measured.

The correct answer is Option 4 i.e. Halocarbonyl.

The IUPAC group prefix for acyl halides is "halocarbonyl-". Acyl halides are compounds where a carbonyl group is bonded to a halogen atom, and the prefix "halocarbonyl-" is used to denote this functional group in complex organic molecules.  In naming, the halogen attached to the carbonyl carbon is reflected by the "halo" prefix (e.g., chloro-, bromo-), and "carbonyl" indicates the carbonyl group. So, a molecule like CH3COCl would be referred to as "chlorocarbonylmethane," where "chlorocarbonyl-" is the prefix for the acyl halide group.

The correct answer is Option 3 i.e. ppm.

The hardness of water is typically expressed in terms of the concentration of calcium carbonate (CaCO₃) equivalents. It is measured in milligrams per liter (mg/L) or parts per million (ppm). This standard unit allows for the comparison of the hardness of water from different sources, regardless of the specific minerals causing the hardness.