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
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
5.1 TABLE 3 below shows the information about the dams that had above ten millioncubic metres of water in January 2016. The terms “fullest and emptiest” are used toindicate the amount of water in the dam in relation to its capacity. Use TABLE 3 to answer the questions that follow. 5.1.1 Identify the fullest dam … Read more
1.1 According to the Arrhenius theory, all bases … A) are proton donors. B) are proton acceptors. C) form H3O+ ions in solution. D) form OH‾ ions in solution. (2) 1.2 The number of neutrons in an atom of N157 is … A) 5 B) 7 C) 8 D) 15 (2) 1.3 Which ONE of the following has the strongest forces between its … Read more
4.1 Study the floor plan of the shopping mall below and answer the questions thatfollow. 4.1.1 Determine the number of 2 x 3 units. (2) 4.1.2 Identify the size of units found at the corners of the mall. (2) 4.1.3 Lindi entered the mall on the West side. She went straight throughRegion V and turned … Read more