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  1. Problems
  2. /Atoms and Molecules
  3. /Molecules, Ions and Formulae

Molecules, Ions and Formulae

Chemistry
+ Upload a Problem
More in Atoms and MoleculesLaws of Chemical CombinationMolecules, Ions and FormulaeThe Mole ConceptMeasurement, Units and Significant FiguresStoichiometry and Concentration
18 problems
Type:
1.
A chemist burns 0.230 g of a liquid that holds only carbon, hydrogen and oxygen. New
High School (11–12) · Stoichiometry and Concentration, Molecules, Ions and FormulaeStemPy LabStemPy Lab
Hard
2.
A fuel gas is 82.8% carbon and 17.2% hydrogen by mass. New
High School (11–12) · Stoichiometry and Concentration, Molecules, Ions and FormulaeStemPy LabStemPy Lab
Medium
3.
Orange crystals used in the laboratory are 26.6% potassium, 35.4% chromium and 38.0% oxygen by mass. New
High School (11–12) · Stoichiometry and Concentration, Molecules, Ions and FormulaeStemPy LabStemPy Lab
Medium
4.
A farmer can buy urea, CO(NH₂)₂, ammonium nitrate, NH₄NO₃, or ammonium sulphate, (NH₄)₂SO₄. New
High School (11–12) · Stoichiometry and Concentration, Molecules, Ions and FormulaeStemPy LabStemPy Lab
Easy
5.
Aluminium sulfate, Al₂(SO₄)₃, is used to make water clear. New
High School (11–12) · The Mole Concept, Molecules, Ions and FormulaeStemPy LabStemPy Lab
Medium
6.
Gallium has two isotopes: gallium-69 of mass 68.926 u and gallium-71 of mass 70.925 u. New
High School (11–12) · The Mole Concept, Molecules, Ions and FormulaeStemPy LabStemPy Lab
Hard
7.
Silicon has three isotopes: silicon-28 of mass 27.977 u (92.23%), silicon-29 of mass 28.976 u… New
High School (11–12) · The Mole Concept, Molecules, Ions and FormulaeStemPy LabStemPy Lab
Medium
8.
Urea, CO(NH₂)₂, is a fertiliser. Find its molecular mass, with C = 12.01 u, O = 16.00 u, N = 14.01… New
High School (11–12) · The Mole Concept, Molecules, Ions and FormulaeStemPy LabStemPy Lab
Easy
9.
Find the valency of the element named in each case.
High School (9–10), General · Molecules, Ions and FormulaeStemPy LabStemPy Lab
Medium
10.
Write the formula of each compound. Use the valencies: Na, K and NH₄ are 1; Mg and Ca are 2; CO₃…
High School (9–10), General · Molecules, Ions and FormulaeStemPy LabStemPy Lab
Easy
11.
Write the formula of calcium phosphate. Calcium has a valency of 2, and the phosphate group, PO₄…
High School (9–10), General · Molecules, Ions and FormulaeStemPy LabStemPy Lab
Medium
12.
Name each of these compounds. KCl; CaO; Na₂CO₃; Mg(NO₃)₂; (NH₄)₂SO₄; Al(OH)₃
High School (9–10), General · Molecules, Ions and FormulaeStemPy LabStemPy Lab
Easy
13.
A tiny crystal of magnesium chloride, MgCl₂, has 350 ions of Mg²⁺.
High School (9–10), General · Molecules, Ions and FormulaeStemPy LabStemPy Lab
Medium
14.
Write the ion formed in each case, and say whether it is a cation or an anion.
High School (9–10), General · Molecules, Ions and FormulaeStemPy LabStemPy Lab
Easy
15.
Each of these is a molecule. Say which are molecules of an element and which are molecules of a…
High School (9–10), General · Molecules, Ions and FormulaeStemPy LabStemPy Lab
Easy
16.
How many atoms of hydrogen, nitrogen and oxygen are there in 2 HNO₃ and 3 H₂O taken together?
High School (9–10), General · Molecules, Ions and FormulaeStemPy LabStemPy Lab
Medium
17.
Give the atomicity of each, and say whether it is monatomic, diatomic, triatomic or has more atoms.
High School (9–10), General · Molecules, Ions and FormulaeStemPy LabStemPy Lab
Easy
18.
Ammonium phosphate, a fertiliser, has the formula (NH₄)₃PO₄.
High School (9–10), General · Molecules, Ions and FormulaeStemPy LabStemPy Lab
Medium