Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.
What is the molar mass of water (H2O)?
18 g/mol
22 g/mol
16 g/mol
12 g/mol
Correct answer is A
The molar mass of water (H2O) is calculated by adding the atomic masses of its constituent elements: 2 hydrogen atoms (each with a molar mass of approximately 1 g/mol) and 1 oxygen atom (with a molar mass of approximately 16 g/mol). Therefore, the molar mass of water is 2 x 1 g/mol + 1 x 16 g/mol = 18 g/mol.
Which organic compound is responsible for the characteristic aroma of fruits?
Alkane
Alkyne
Ester
Amine
Correct answer is C
Esters are organic compounds that have a pleasant, fruity aroma. They are responsible for the characteristic smells of fruits and many other fragrant substances.
Which of the following factors does NOT affect the rate of a chemical reaction?
Concentration of reactants
Presence of a catalyst
Molecular weight of products
Temperature
Correct answer is C
The molecular weight of products is not directly related to the rate of a chemical reaction. The factors that affect the reaction rate include concentration of reactants, temperature, presence of catalysts, surface area, and the nature of the reactants and products.
When an acidic solution is diluted, what happens to its pH?
It depends on the specific acid
It decreases
It remains the same
It increases
Correct answer is D
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