Atoms and Molecules Quiz

Which postulate of Dalton’s atomic theory is the result of the law of conservation of mass?

• Atoms are indivisible and cannot be created or destroyed.
• Atoms can be transformed into energy through nuclear reactions.
• Atoms are composed of smaller particles called quarks.
• Atoms can be created under certain conditions.

Which postulate of Dalton’s atomic theory can explain the law of definite proportions?

• The postulate that all atoms are identical in mass and properties.
• The postulate that atoms cannot be created or destroyed in a chemical reaction.
• The postulate that elements can exist in multiple forms depending on temperature.
• The postulate that compounds are formed from fixed ratios of atoms.

What is a Molecule?

• A molecule is a single atom.
• A molecule is a type of chemical reaction.
• A molecule is a group of two or more atoms bonded together.
• A molecule is a collection of molecules.

Write down the formulae of (i)sodium oxide (ii)aluminium chloride (iii)sodium sulphide (iv)magnesium hydroxide

• Na2O2, AlCl2, NaS, Mg(OH)3
• Na3O, AlCl4, Na2S2, Mg(OH)
• NaCl, Al2Cl6, Na2SO4, MgO
• Na2O, AlCl3, Na2S, Mg(OH)2

How many atoms are present in a (i)H2S molecule and (ii)PO43– ion?

• H2S: 3 atoms; PO43–: 3 atoms
• H2S: 4 atoms; PO43–: 6 atoms
• H2S: 2 atoms; PO43–: 4 atoms
• H2S: 3 atoms; PO43–: 5 atoms

Calculate the molecular masses of C2H4 and NH3.

• C2H4: 32.04 g/mol, NH3: 15.03 g/mol
• C2H4: 28.05 g/mol, NH3: 17.034 g/mol
• C2H4: 30.07 g/mol, NH3: 18.02 g/mol
• C2H4: 26.98 g/mol, NH3: 20.06 g/mol

What are polyatomic ions? Give examples.

• Examples of polyatomic ions include sulfate (SO42-), nitrate (NO3-), and ammonium (NH4⁺).

• Calcium carbonate (CaCO3)
• Sodium chloride (NaCl)
• Iron oxide (Fe2O3)

What is the chemical formula for (i)calcium phosphate (ii)iron(III) oxide (iii)potassium nitrate (iv)zinc sulfate?

• Ca3P2O8, Fe2O3, KNO2, ZnSO3

• Ca3(PO4)2, Fe2O3, KNO3, ZnSO4

• Ca(PO4)2, FeO3, K2NO3, ZnS

• Ca3(PO4)2, FeO, KNO3, ZnO

How many atoms are present in a (i)C6H12O6 molecule and (ii)SO42– ion?

• C6H12O6: 24 atoms; SO42–: 4 atoms

• C6H12O6: 12 atoms; SO42–: 6 atoms

• C6H12O6: 18 atoms; SO42–: 4 atoms

• C6H12O6: 24 atoms; SO42–: 6 atoms

Which postulate of Dalton’s atomic theory explains the law of multiple proportions?

• The postulate that atoms of different elements can combine in simple whole-number ratios.

• The postulate that all atoms are identical in mass and properties.

• The postulate that compounds are formed from fixed ratios of atoms.

• The postulate that atoms cannot be created or destroyed in a chemical reaction.