The student placed a Bunsen burner under one end of the metal rods and started Table 1 shows the results. a stopwatch. Table 1 As the other end of each metal rod heated up, the wax melted and the pin dropped. The student recorded the time at which each pin dropped. Metal Time at which the pin dropped in seconds Aluminium 35 0 1. 2 What is one control variable in the investigation? [1 mark] Copper 20 Tick () one box. Iron 45 The length of the metal rods Tin 52 The metal that each rod is made from 0 1. 4 Which metal is the best thermal conductor? The time at which each pin dropped Use Table 1- [1 mark] Tick (v ) one box. 0 1. 3 The student wore safety glasses during the investigation. Give one other safety precaution that the student should take when carrying out the Aluminium investigation. [1 mark] Copper Iron Tin 0 1. 5 The student repeated the investigation with a hotter flame from the Bunsen burner. Give one similarity and one difference between the results that the student would observe and the results in Table 1. [2 marks] Similarity Difference [Total 6 marks]Answer all questions in the spaces provided 0 1 Metals are good thermal conductors. 0 1. 1 Complete the sentence, Choose the answer from the box. (1 mark] electrons ions neutrons protons Metals are good thermal conductors because they contain free A student investigated the rate of thermal conduction in metal rods. Each rod was made from a different metal. A pin was attached to the end of each metal rod with wax. Figure 1 shows some of the equipment used. Figure 1 Metal rod Pin Wax Tripod Bunsen burner