2023 - JAMB Chemistry Past Questions and Answers - page 6

The atomic number of an element is the number of protons in the nucleus of an atom of that element.

For aluminium, which has the chemical symbol Al, the atomic number is 13. This means that a neutral aluminium atom has 13 protons in its nucleus.

The atomic number is a fundamental property of an element and determines its place in the periodic table. In the case of aluminium, it is a metal commonly used in various industries due to its lightweight, corrosion resistance, and other favourable properties.

The state of matter in which particles are widely spaced and move freely with high kinetic energy is a gas.

In the gaseous state, particles have enough energy to overcome attractive forces, allowing them to move independently and occupy a large volume.

Calcium belongs to the alkaline earth metals group in the periodic table. Members of this group, including calcium, have two valence electrons and exhibit similar chemical properties.

In the electrochemical series, also known as the reactivity series, Hydrogen is placed at the top.

The electrochemical series is a list of elements in the order of their standard electrode potentials (or redox potentials). 

Elements at the top of the series have a greater tendency to gain electrons and form negative ions, while elements below hydrogen tend to lose electrons and form positive ions.

The trend for ionization energy across a period in the periodic table is that it increases from left to right.

Ionization energy is the energy required to remove an electron from an atom, and as you move across a period from left to right, the effective nuclear charge increases, making it more difficult to remove an electron, and hence, ionization energy increases.

Ethanoic acid, commonly recognized as acetic acid, is a organic compound with the molecular formula CH3COOH.

It is a weak acid with a distinctive pungent odour and is widely known for its presence in vinegar. Acetic acid is formed through the oxidation of ethanol in the presence of oxygen, a process that occurs during the fermentation of certain substances.

This versatile acid plays a crucial role in various applications, including food preservation, pickling, and as a condiment. Its chemical properties make it an essential component in the culinary world and industrial processes.

A blue litmus paper turning red indicates that the solution is acidic.

Blue litmus paper turns red in acidic solutions and remains blue in neutral or basic solutions.

When an acidic solution is diluted by adding more solvent (usually water), the concentration of hydrogen ions (H+) decreases.

As a result, the pH of the solution increases, making it less acidic and potentially moving towards a more neutral pH.

Dilution of an acidic solution leads to an increase in pH.

The Haber process is a method for synthesizing ammonia (NH₃) from nitrogen (N₂) and hydrogen (H₂) gases, typically carried out under high pressure and with the aid of an iron catalyst.

This industrial process is crucial for producing ammonia, a key component in fertilizers and various chemical applications.

Methane is a primary constituent of crude oil. Crude oil is a complex mixture of hydrocarbons, and methane is the simplest hydrocarbon, consisting of a single carbon atom bonded to four hydrogen atoms.

While other hydrocarbons like pentane, ethanol, and heptane may be present in crude oil, methane is a fundamental component and is commonly found in natural gas associated with petroleum deposits.