2021 - JAMB Chemistry Past Questions and Answers - page 2

Carbon dioxide (CO₂) is the primary greenhouse gas emitted through human activities

CO₂ is a colourless gas having a faint sharp odour and a sour taste. 

Global warming is the long-term heating of the Earth's surface observed since the pre-industrial period (between 1850 and 1900) due to human activities, primarily fossil fuel burning, which increases heat-trapping greenhouse gas levels in Earth's atmosphere. More

Oxygen is a reactive element that readily forms compounds. * **Kerosene** is a hydrocarbon, primarily composed of carbon and hydrogen atoms. It does not contain oxygen. * **Soil** contains various components, including air, which contains oxygen. * **Glass** is typically made of silicon dioxide (silica) and other oxides, so it contains oxygen. * **Cement** contains oxides such as calcium oxide, so it contains oxygen.

Sublimation is the transition of a substance directly from the solid phase to the gas phase without passing through the intermediate liquid phase.

Substances that sublime readily include iodine, dry ice, menthol, and camphor.

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The N shell is the fourth orbit with 32 maximum number of electrons using 2n\(^2\)

James Chadwick, a British physicist, in May 1932.

Calcium trioxocarbonate (IV) occurs abundantly in the earth's crust as limestone, chalk and marble. Eggshell is mainly made up of calcium carbonate (CaCO3) crystals.

Surface tension. The surface tension forces become smaller as the distance between water molecules increases, the intervening soap molecules decrease the surface tension.

Fluorine (F) is the most reactive chemical element and the lightest member of the halogen elements.

The great reactivity of fluorine largely stems from the relatively low dissociation energy, a standard measure for bond energies, of the F―F bond (37.7 kilocalories per mole) and its ability to form stable strong bonds with essentially all the other elements. More

The mass number is the sum of the number of protons and neutrons present in the nucleus of an atom.

Avogadro's number is an absolute number: there are 6.022×10\(^23\) elementary entities in 1 mole.

Helium has a molar mass of 4.0 grams per mole. So one mole of Helium has a mass of 4.0 grams.