Q36. Angle of incidence is less than critical angle so total internal reflection does not take place. However, when refraction takes place, not all light refracts. (Some reflects and some refracts). So C.
Q34. To have greater sensitivity, there should be a greater volume change when there is a temperature change. Hence, the cylinder should be thinner. Also, if the sphere below is larger, there is more liquid. So there would be greater volume change when temperature changes. So B.
Q26. Calcium carbonate (so-called limestone) is used for neutralisation, as it reacts with acid to increase pH (neutralise). So A
Q18. There wouldn't be a colour change, so A is inadequate. But carbon dioxide is produced, so measuring gas volume and measuring mass change (mass lost by the release of carbon dioxide) would be appropriate. So D.
Q37. NTC thermistor changes resistance when there is a change in temperature, while LDR changes resistance when there is a change in light intensity. Hence, for this question, the circuit should contain a NTC thermistor (Not C nor D). Also, the question says that it measures potential difference between X and Y; hence, there should be some sort of change in voltage between X and Y. That is achieved by placing a NTC thermistor between those two points. So the answer would be B.
Q20. In this reaction, ammonium ion (NH4, this is a cation) loses one hydrogen to become ammonia (NH3). During the reaction, ammonium ion gains a negative charge, being reduced. Electron acceptors are ions or molecules that act as oxidising agents in chemical reactions. Hence, ammonium ion would be an electron acceptor, so C.
Ok, thank you.
Hi Harry, thank you for your questions.
Q36. Angle of incidence is less than critical angle so total internal reflection does not take place. However, when refraction takes place, not all light refracts. (Some reflects and some refracts). So C.
Q34. To have greater sensitivity, there should be a greater volume change when there is a temperature change. Hence, the cylinder should be thinner. Also, if the sphere below is larger, there is more liquid. So there would be greater volume change when temperature changes. So B.
Q26. Calcium carbonate (so-called limestone) is used for neutralisation, as it reacts with acid to increase pH (neutralise). So A
Q18. There wouldn't be a colour change, so A is inadequate. But carbon dioxide is produced, so measuring gas volume and measuring mass change (mass lost by the release of carbon dioxide) would be appropriate. So D.
Q37. NTC thermistor changes resistance when there is a change in temperature, while LDR changes resistance when there is a change in light intensity. Hence, for this question, the circuit should contain a NTC thermistor (Not C nor D). Also, the question says that it measures potential difference between X and Y; hence, there should be some sort of change in voltage between X and Y. That is achieved by placing a NTC thermistor between those two points. So the answer would be B.
Q20. In this reaction, ammonium ion (NH4, this is a cation) loses one hydrogen to become ammonia (NH3). During the reaction, ammonium ion gains a negative charge, being reduced. Electron acceptors are ions or molecules that act as oxidising agents in chemical reactions. Hence, ammonium ion would be an electron acceptor, so C.