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A student tested a solution by adding aqueous sodium hydroxide. A precipitate was not seen because the reagent was added too quickly. What could not have been present in the solution? Al3+, Ca2+, NH4+, Zn2+
Which substance has a giant molecular structure at room temperature? methane, sand, sodium chloride, water
When a covalent liquid boils its molecules become more widely spaced.Which property of the molecules has the most influence on the energy required to boil a covalent liquid the forces of attraction between the molecules, the reactivity of the molecules, the shape of the mo
The atoms 64/29 Cu and 65/30 Zn have the same nucleon number., number of electrons., number of neutrons., proton number.
Why does molten sodium chloride conduct electricity? An electron is completely transferred from sodium to chlorine, Sodium ions are only weakly attracted
Which equation describes the most suitable reaction for making lead sulphate? Pb + H2SO4 ? PbSO4 + H2, PbCO3 + H2SO4 ? PbSO4 + CO2 + H2O, Pb(NO3)2 + H2SO4 ? PbSO4 + 2HNO3, Pb(OH)
In which oxide does X have the same oxidation state as in the chloride, XCl3? X3O, X2O, XO2, X2O3
One mole of a sample of hydrated sodium sulphide contains 162 g of water of crystallisation. What is the correct formula of this compound? Na2S.3H2O, Na2S.5H2O , Na2S.7H2O , Na2S.9H2O
When dilute sulphuric acid is electrolysed between platinum electrodes, which statements are correct? 1 Hydrogen is released at the cathode. 2 Oxygen is released at the anode. 3 Sulphur is released at the anode. 4 The acid becomes more dilute. 1 and 2, 1 and 3, 2 and 4, 4 only
Which of the following is an endothermic reaction? the combustion of ethanol in air, the formation of a carbohydrate and oxygen from carbon dioxide an
At 400 °C the reaction between hydrogen and iodine reaches an equilibrium.H2(g) + I2(g) 2HI(g) ?H = –13 kJ Which change in conditions would increase the percentage of hydrogen iodide in the equilibrium mixture? a decrease in pressure, a decrease in temperature, an increase in pressure, an increase in temper
Sulphur dioxide reacts with aqueous bromine according to the following equation. SO2(g) + Br2(aq) + 2H2O(l) ? H2SO4(aq) + 2HBr(aq) Which element has been oxidised? bromine, hydrogen, oxygen, sulphur
When 20 cm3 of a 2 mol/dm3 solution of potassium hydroxide is mixed with 20 cm3 of a 1 mol/dm3 solution of sulphuric acid, the temperature of the mixture rises. What best explains this? Sulphuric acid is a strong acid., The potassium hydroxide solution is more concentrated than the sul
Which observation is typical of a solid non-metal element? It reacts vigorously with chlorine., It conducts electricity, It has more than one oxidation state,
Which equation represents the reaction between hydrochloric acid and sodium hydroxide? Cl– + Na+ ? NaCl, 2H+ + O2– ? H2O, 1/2 O2 + H2 ? H2O2, H+ + OH– ? H2O
The following statements about dilute sulphuric acid are all correct A white precipitate is formed when aqueous barium chloride is added, The solution turns anhydrous co
Ammonia gas is produced when solid ammonium chloride is heated with calcium hydroxide, calcium sulphate., hydrochloric acid., magnesium nitrate.
Sulphur and selenium (Se) are in the same group of the Periodic Table.From this, we would expect selenium to form compounds having the formulae SeO, Na2Se and NaSeO4., SeO2, Na2Se and NaSeO4., SeO2, Na2Se and Na2SeO4., SeO3, NaSe and NaSeO4.
X and Y are diatomic elements. X is less reactive than Y. What are elements X and Y? chlorine iodine, fluorine nitrogen, iodine bromine, oxygen nitrogen
A metal X, in Group I of the Periodic Table, would be expected to form a nitrate of formula X(NO3)2., form an acidic oxide., form an insoluble chloride., produce hydr
Three types of steel have different properties. steel 1 easily shaped steel 2 brittle steel 3 resistant to corrosion What are the names of these three types of steel? high carbon mild stainless, high carbon stainless mild, mild high carbon stainless, mild
Aluminium is used to make saucepans because of its apparent lack of reactivity. Which property of aluminium explains its unreactivity? It has a high electrical conductivity., It has a low density., It has a surface layer of oxide., It
A solid substance Z burns in air to form a product that is gaseous at 20 °C. What is Z? hydrogen, carbon monoxide, carbon, magnesium
Which compound has more than two carbon atoms per molecule? ethyl ethanoate, ethene, ethene, ethanoic acid
Alkanes are a homologous series of organic compounds Which statement about alkanes is correct? Their boiling points increase as the length of the carbon chain increases., Their general formula is