Stoichiometry — IGCSE Chemistry (0620) questions by topic

Which row shows the correct formula for the named substance? substance formula --- --- --- A cobalt(II) chloride Cu2Cl B sodium carbonate Na2CO3 C xenon Xe2 D ammonium sulfate…

The equation shows the thermal decomposition of magnesium carbonate. MgCO3 → MgO + CO2 [Mr: MgCO3, 84] Which mass of magnesium oxide is formed when 21.0 g of magnesium carbonate…

In the molecules CH4, HCl and H2O, which atoms use all of their outer shell electrons in bonding? A C and Cl B C and H C Cl and H D H and O

The equation for the reaction of magnesium with oxygen is shown. 2Mg + O2 - 2MgO Which mass of oxygen reacts exactly with 6 g of magnesium? A 2 g B 4 g C 8 g D 16 g

Which equation represents the reaction of magnesium with dilute hydrochloric acid? A Mg(s) + 2HCl(aq) - MgCl2(aq) + H2(g) B Mg(s) + 2HCl(l) - MgCl2(s) + H2(g) C 2Mg(s) + 2HCl(aq)…

The relative formula mass, Mr, of calcium carbonate, CaCO3, is 100. What is the mass of carbon present in 100 g of calcium carbonate? A 12 g B 36 g C 40 g D 60 g

What is the definition of relative atomic mass? A It is the average mass of the isotopes of an element compared to 1/12 th of the mass of an atom of 12-C. B It is the total mass…

The only naturally occurring isotopes in a sample of europium are ¹⁵¹Eu and ¹⁵³Eu. This sample of europium has a relative atomic mass, Ar, of 152. What is the percentage of ¹⁵¹Eu…

Three organic molecules are described. - The molecular formula of propanoic acid is CH₃CH₂COOH. - The molecular formula of lactic acid is CH₃CH(OH)COOH. - A glucose molecule…

Calcium carbonate reacts with dilute hydrochloric acid. The equation for the reaction is shown. CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂ 1.00 g of calcium carbonate is added to 50.0 cm³…

When 65 g of zinc reacts with 32 g of sulfur, 97 g of zinc sulfide is produced. When 65 g of zinc reacts with 40 g of sulfur, the mass of zinc sulfide produced is still 97 g.…

Aluminium reacts with iron(III) oxide to form aluminium oxide and iron. Which chemical equation for the reaction between aluminium and iron(III) oxide is correct? A Al + FeO - AlO…

The concentration of a solution of aqueous sodium hydroxide is 0.50 mol/dm^3. Which mass of sodium hydroxide is used to make 500 cm^3 of this solution? A 10 g B 20 g C 40 g D 160 g

A compound is analysed and found to contain 85.7% carbon and 14.3% hydrogen only. What is its empirical formula? A CH B CH2 C C2H4 D C6H

Aqueous barium hydroxide, Ba(OH)2, reacts with dilute nitric acid, HNO3. The products are aqueous barium nitrate, Ba(NO3)2, and water. In a titration, 15.2 cm3 of 0.75 mol/dm3…

This question is about sea water and the substances found in sea water. Table 2.1 shows the masses of the compounds formed when 1000 cm^3 of sea water is evaporated. Table 2.1…

A covalent molecule, M, contains four shared pairs of electrons. What is M? A ammonia, NH3 B hydrogen chloride, HCl C methane, CH4 D water, H2O

Iron(III) oxide is reduced by carbon monoxide to produce iron and carbon dioxide. What is the balanced equation for this reaction? A Fe2O3 + 2CO → 2Fe + 2CO2 B Fe2O3 + 3CO → 2Fe +…

The equation for the reaction between magnesium and dilute hydrochloric acid is shown: Mg + 2HCl → MgCl2 + H2 Which mass of magnesium chloride is formed when 48.0 g of magnesium…

Which row shows the correct formulae of lead(II) bromide and butane? (columns: lead(II) bromide; butane) A PbBr2; C4H8 B PbBr2; C4H10 C Pb2Br; C4H8 D Pb2Br; C4H10

Calcium phosphate forms when calcium chloride and sodium phosphate solutions react together: x CaCl2 + y Na3PO4 → 2Ca3(PO4)2 + 12NaCl Which values of x and y balance the equation?…

What is the definition of relative molecular mass, Mr? A It is the average mass of the isotopes in a compound. B It is the sum of the atomic numbers in a compound. C It is the sum…

Which statement is the correct definition for molecular formula? A an atom or group of atoms that determine the chemical properties of a compound B a structure which shows all the…

A compound, T, has the formula CH3Cl. Three statements about this compound are listed: 1 A molecule of the compound contains five atoms. 2 A molecule of the compound contains five…

How many electrons are shared in one molecule of nitrogen and in one molecule of ethene? (columns: nitrogen; ethene) A 2; 12 B 2; 8 C 6; 12 D 6; 8

What is the total number of electrons in one molecule of ammonia, NH3? A 6 B 8 C 10 D 11

When heated, copper(II) oxide, CuO, reacts with ammonia, NH3: 3CuO + 2NH3 → 3Cu + N2 + 3H2O 8.5 g of ammonia reacts with an excess of copper(II) oxide to produce 26.4 g of copper.…

What is the empirical formula of ethanoic acid? A CHO B CH2O C C2H2O D C2H4O2

Magnesium chloride, MgCl2, contains magnesium ions and chloride ions. How many chloride ions are present in two moles of magnesium chloride? [Avogadro constant = 6.02 × 10²³ per…

Which diagram (A, B, C or D) shows the arrangement of the outer shell electrons in a molecule of water? Each diagram shows an O atom bonded to two H atoms with different…

The structure of glycine is shown (H2N-CH2-COOH). Which row is correct? (columns: formula of glycine; number of different elements in glycine) A CH5O2N; 10 B C2H5O2N; 4 C C2H5O2N;…

The incomplete equation for photosynthesis is shown: wCO2 + xH2O → P + yO2 Compound P is a product of the reaction. Which row describes the values of w, x and y and gives the…

The concentration and volume of an aqueous alkali are known. Which additional information is required to calculate the number of moles of acid needed to neutralise the aqueous…

Which molecule contains a double covalent bond between two atoms of the same element? A carbon dioxide B ethanol C ethene D nitrogen

The equation for the reaction of iron(III) oxide with carbon monoxide is shown: Fe2O3 + 3CO → 2Fe + 3CO2 What is the percentage yield of iron when 16.8 g of carbon monoxide reacts…

What is the volume of 14.5 g of gaseous butane, C4H10, at room temperature and pressure? [Mr C4H10 = 58; molar gas volume = 24 dm³/mol at r.t.p.] A 96.0 cm³ B 6.0 cm³ C 96.0 dm³ D…

Many organic compounds contain carbon and hydrogen only. Organic compound A has the composition by mass C 82.76%, H 17.24%. Calculate the empirical formula of compound A. [Ar: C =…

A carboxylic acid reacts with an alcohol to produce an ester and water. Under certain conditions, this reaction can be reversed so an ester reacts with water to produce a…

Many organic compounds contain carbon and hydrogen only. An organic compound A has the composition by mass C 83.33%, H 16.67%. Calculate the empirical formula of compound A. [Ar:…

Nitrogen monoxide, NO, is a simple molecular compound. Which row shows the properties of nitrogen monoxide? boiling point electrical conductivity --- --- --- A high good B high…

What is the relative molecular mass, Mr, of sulfuric acid, H2SO4? A 81 B 82 C 97 D 98

The equation for the production of ammonia, NH3, is shown. N2(g) + 3H2(g) - 2NH3(g) Which mass of nitrogen is required to make 51 tonnes of ammonia? A 21 tonnes B 25.5 tonnes C 42…

Which symbol equation represents the reaction between aqueous sodium hydroxide and dilute sulfuric acid? A Na2OH + H2SO4 - 2NaSO4 + H2O B Na(OH)2 + H2SO4 - Na2SO4 + 2H2O C 2NaOH +…

What is the relative formula mass of magnesium bromide? A 47 B 82 C 104 D 184

Magnesium burns in oxygen to form magnesium oxide. The equation for the reaction is shown. 2Mg + O2 - 2MgO Which mass of magnesium oxide is formed when 48 g of magnesium is…

Propane, C3H8, is burned in a limited amount of oxygen. Which equation represents this reaction? A C3H8 + 5O2 - 3CO2 + 4H2O B C3H8 + 4O2 - 3CO + 4H2O C C3H8 + 4O2 - 3CO2 + 2H2O +…

The isotope of which element is used to define the relative atomic mass of other elements? A sulfur B oxygen C nitrogen D carbon

Which gas has the lowest rate of diffusion at room temperature and pressure? A the gas produced when ammonium chloride is heated with aqueous sodium hydroxide B the gas which…

Sulfur is a simple molecule with the formula S8. Which row describes and explains the melting point of sulfur? melting point explanation --- --- --- A high the covalent bonds…

What is the formula of iron(III) oxide? A FeO B Fe3O4 C FeO2 D Fe2O3

Calcium carbonate is heated. Calcium oxide and carbon dioxide gas are formed. The equation for the reaction is shown. CaCO3 - CaO + CO2 225 kg of calcium carbonate is heated until…

The equation for the decomposition of ammonium carbonate, (NH4)2CO3, is shown. (NH4)2CO3(s) - 2NH3(g) + CO2(g) + H2O(l) [Mr of (NH4)2CO3 = 96] The total volume of gas produced is…

What is the empirical formula of a compound that contains 3.66 g of hydrogen, 37.8 g of phosphorus and 58.5 g of oxygen? A H6P2O6 B H4PO4 C H3PO3 D HPO

A sample of iridium has a relative atomic mass of 192.29. The sample contains two isotopes only. 64.50% of the sample is 193-Ir. What is the other isotope in the sample? A 189-Ir…

Ammonium iron(III) citrate contains in its formula: more than one ammonium ion; one iron ion; two C6H4O7 4- ions. What is the formula of ammonium iron(III) citrate? A…

Silicon(IV) oxide reacts with chlorine and carbon to form liquid silicon(IV) chloride, SiCl4, and carbon dioxide gas. If the reaction is carried out at r.t.p., which symbol…

The structure of ethene is shown (CH2=CH2). How many hydrogen atoms and how many carbon atoms are in one mole of ethene? hydrogen atoms carbon atoms --- --- --- A 2.4 x 10^24 1.2…

Nitrogen molecules are diatomic. State the meaning of the term diatomic.

Hydrogen chloride has a simple molecular structure. State two physical properties of a compound with a simple molecular structure.

Sulfur forms two chlorides, P and Q. Chloride P has the formula S2Cl2. Chloride Q has the formula SCl2. Both chlorides are covalently bonded and have low melting points. Suggest,…

This question is about compounds of tin. Tin(IV) oxide has the formula SnO2. The relative formula mass, Mr, of SnO2 is 151. Calculate the percentage by mass of tin in SnO2.

This question is about sulfur and compounds of sulfur. Sulfur is converted into sulfuric acid, H₂SO₄, by the Contact process (stage 1: molten sulfur → sulfur dioxide; stage 2: SO₂…