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In a sample of air at 25 ° C,the molecules of oxygen , nitrogen and carbon dioxide all move with different average speed. Which of the following lists the molecules in order of decreasing average speed : carbon dioxide, oxygen, nitrogen, nitrogen, oxygen , carbon dioxide, oxygen ,carbon dioxide,nitrogen
which of the following is the best method of obtaining pure water from ink ? Chromatography, distillation, filtration, freezing
The relative molecular mass ,M r of copper (II) sulphate CuSO4 is 160.the relative molecular mass ,M r of water is 18 what is the percentage by mass of water in copper(II) sulphate crystals,CuSO4.5H2O ? 18 X 100 /160, 5 X 18 X100 /160 + 18, 18 X 100 /160 + 18, 5 X 18 X 100 /160 + 18
An element X has two isotopes 238 X and 235 X how does 238 X differ from 235 X ? it has 3 more protons and 3 more electron , it has 3 more protons but no more electron , it has 3 m
The formulae of the ions of four electron are shown below O2- F- Li+ Mg2+ which statement about these is correct ? They all have : the same number of electrons in their outer shells, the same electronic structure as a noble gas , t
What happens when sodium chloride melts ? Covalent bond in agiant lattice are broken , Electron are relased from atom, Electrostatic force of
what is the concentration of iodine ,I2 molecules in a solution containing 2.54 g of iodine in 250 cm3 of solution ? 0.01 mol/dm3, 0.02 mol/dm3, 0.04 mol/dm3, 0.08 mol/dm3
The formula of an oxide of uranium is UO2 what is the formula of corresponding chloride ? UCl2, UCl4, U2Cl, U4Cl
The equation for the burning of hydrogen in oxygen is shown below 2 H2(g) + O2(g) ? 2H2O(g) which information does this equation about the reaction ? 36 g of stem can be obtained from 16 g of oxygen, 2 g of hydrogen combine 1 g of oxygen, 2 mol
which of the folowing changes is endothermic ? H(g) + Cl(g) ? HCl(g), H2O(g) ? 2H(g) + O(g), H2O(I) ? H2O(S), 2H2(G) + O2(G) ? 2H2O(I)
Which change will increase the speed of the reaction between 1 mol of each the gases X and Y ? a decrease in surface area of the catayst, a decrease in temperature, a decrease in the volume of th
which method of preparation of pure salt solution requires the use of a pipette and burette ? BaCl(aq) + H2SO4(aq) ? BasO4(s) + 2HCl (aq), CUO(S) + 2HCl(aq) ? CUCL2(aq) + H2O(I), KOH(aq) + HCl(
Which statement about the maunfcture of ammonia by the Haber Process is correct ? The reactants and product are element, The reactants and product are gases, The reactants and produc
Which of the following occuring in the contact process ? Sulphur dioxide is dissolved in water, Sulphur trioxide is dissolved in water, Sulphur dioxide is di
Use the Periodic table to decide which element has all four of the properties shown High melting point Variable oxidation states good electrical conductivity form coloured compound : Caesium Cs, Cobalt Co, Iodine I, Strontium Sr
iron rust when exposed to oxygen in the presence of water which of these method will not slow down the rate of rusting of an iron roof ? Attaching strips of copper to it , Coating it with plastic, galvanising it with zinc, Painting it
why does aluminium have an apparent lack of reactivity ? Auminium has a coating of aluminium oxide preventing futher reaction, Auminium is low in the reactiv
which oxide can be reduced to the metal by hydrogen ? Calcium oxide, Copper (II) oxide, Magnesium oxide, Sodium oxide
The water in a lake contains the following dissolved substance mineral Nitrate oxygen phosphates sewage 1, 2, 3, 4
The equation represent the conversion of starch to a simple sugar ( C6 H10 O5) + nH2O ? n C6 H12 O6 this reaction is an example of Condensation, Hydrogenation, Hydrolysis, Polymersation
Methane , CH4 the first member of alkane homologous series has a boiling point of 161 ° C which molecular formula and boiling point could be for another alkane ? C2H4 , -88 , C2H4 , -185 , C3H6 ,-69, C3H8 ,-42
a STUDENT CARRIES out three test on a gas X damp red litmus paper , stay red aqueous bromine stays brown , lighted splint gas burns which gas could be X : Ammonia, Ethene, methane, Oxygen
An organic compound Y react with sodium hydroxide to give a compound with formula C3H5O2Na what compound Y ? ethanol, propane, Propanoic acid, propanol
Which compound has an addition reaction with chlorine ? C2H4, C2H6, C2H5OH, CH3CO2H