devozeeba 1.1.1 How many entrances can you use to access the centre? (2) 1.1.2 You get a call from your friend. The two of you lost each other in thecentre. Your friend is at the Automatic Teller Machine (ATM) atShop No. 40. You are waiting for your friend at Entrance No. 2.Explain to your friend the … Read more
Electronegativity of atoms may be used to explain the polarity of bonds. 2.1 Define the term electronegativity. (2) 2.2 Draw the Lewis diagram of an oxygen difluoride molecule. (2) 2.3 Calculate the electronegativity difference between O and F in oxygendifluoride and predict the polarity of the bond. (2) 2.4 A polar bond does not always … Read more
A barium hydroxide solution, Ba(OH)2(aq), reacts with a nitric acid solution, HNO3(aq), according to the following balanced equation: Ba(OH)2(aq) + 2HNO3(aq) → Ba(NO3)2(aq) + 2H2O(ℓ) The potential energy graph below shows the change in potential energy for this reaction. 7.1 Is this reaction ENDOTHERMIC or EXOTHERMIC? Give a reason for the answer. (2) 7.2 Use … Read more
6.1 Sodium thiosulphate, Na2S2O3(s), reacts with 200 cm3 of a hydrochloric acid solution, HCℓ(aq), of concentration 0,2 mol·dm-3 according to the following balanced equation: Na2S2O3(s) + 2HCℓ(aq) → 2NaCℓ(aq) + S(s) + SO2(g) + H2O(ℓ) 6.1.1 Define the term concentration of a solution. (2) 6.1.2 Calculate the number of moles of HCℓ(aq) added to the … Read more
The fizz produced when an antacid dissolves in water is caused by the reaction between sodium hydrogen carbonate (NaHCO3) and citric acid (H3C6H5O7). The balanced equation for the reaction is: 3NaHCO3(aq) + H3C6H5O7(aq) → Na3C6H5O7(aq) + 3CO2(g) + 3H2O(ℓ) 5.1 Write down the FORMULA of the substance that causes the fizz when the antacid dissolves in … Read more
A learner investigates the relationship between the pressure and volume of an enclosed DIATOMIC gas at 25°C. He records the volume of the gas for different pressures in the table below. 4.1 Write down the name of the gas law being investigated. (1) Answer QUESTION 4.2 and QUESTION 4.3 on the attached ANSWER SHEET. 4.4 … Read more
A heavy object is lifted using two ropes and two pulleys, as shown in the diagram below. The two pulleys are a distance x apart. The force FA, in rope A, is 730 N and the force FB, in rope B, is 1 440 N. Rope A makes an angle of 70° with the horizontal … Read more
3.1 The boiling point of compounds A to E are given in the table below. 3.1.1 Define the term boiling point. (2) 3.1.2 Calculate the molecular mass of compound D. (1) 3.1.3 In what phase is compound B at 25 °C? (1) 3.1.4 Name the type of intermolecular force present in compound A. (1) 3.1.5 … Read more
Molecules such as CO2 and H2O are formed through covalent bonding. 2.1 Define the term covalent bonding. (2) 2.2 ONE of the above molecules has lone pairs of electrons on the central atom. Draw the Lewis diagram for this molecule. (2) 2.3 H3O+ is formed when H2O forms a dative covalent bond with an H+ … Read more
Four options are provided as possible answers to the following questions. Eachquestion has only ONE correct answer. Choose the answer and write only theletter (A–D) next to the question number (1.1–1.10) in the ANSWER BOOK, forexample 1.11 E. 1.1 Vector P and vector –P are acting on a common point O. The angle betweenthe two … Read more