Chemical Combination
Chemistry · 50 practice questions
Laws of definite, multiple and reciprocal proportions; law of conservation of matter; Gay-Lussac's law of combining volumes; Avogadro's law; chemical symbols, formulae, equations and their uses; relative atomic mass (based on ¹²C = 12); the mole concept and Avogadro's number; stoichiometry of reactions.
- Perform calculations involving formulae, equations, chemical composition and the mole concept.
- Deduce chemical laws from given expressions, statements or data.
- Interpret graphical representations related to these laws.
- Deduce the stoichiometry of chemical reactions.
Try a few questions
- Practice question 1
A chemical symbol, compared to a chemical formula, mainly represents
- A.one atom of an element, whereas a formula represents a fixed combination of atoms in a compound
- B.a fixed combination of atoms, whereas a formula represents just one atom
- C.exactly the same thing as a chemical formula in every case
- D.the exact mass of one mole of a substance
Show the answer
A. one atom of an element, whereas a formula represents a fixed combination of atoms in a compound
A symbol denotes a single elemental atom, while a formula captures how atoms combine within a compound.
- Practice question 2
The percentage of oxygen by mass in calcium trioxocarbonate(IV), CaCO₃ (Ca = 40, C = 12, O = 16, molar mass = 100), is
- A.40%
- B.48%
- C.12%
- D.16%
Show the answer
B. 48%
Percentage O = (48 ÷ 100) x 100 = 48%, since three oxygen atoms contribute 3 x 16 = 48 to the molar mass.
- Practice question 3
A mole is defined as the amount of substance that contains
- A.exactly 12 grams of any given substance
- B.exactly one gram of hydrogen atoms
- C.an arbitrary, undefined number of particles
- D.the same number of elementary particles as there are atoms in exactly 12g of carbon-12
Show the answer
D. the same number of elementary particles as there are atoms in exactly 12g of carbon-12
This definition anchors the mole concept directly to the carbon-12 standard used for relative atomic mass.
More UTME Chemistry topics
Practise with instant feedback
Answer questions one at a time and see the right answer and the reason straight away. Free to start.
Start practising