Question

a student recorded the temperature of a solution every 30 seconds for 3 minutes while the solution was being heated. without drawing an actual graph, indicate which of the following describes a line graph of the given data.
temperature of a solution while heating

time (s)	temperature (°c)
30	35
60	48
90	61
120	74
150	87
180	100

a) a straight horizontal line
b) a straight vertical line
c) a straight line rising from right to left
d) a straight line rising from left to right

Explanation:

We analyze the relationship between time (x - axis, left to right) and temperature (y - axis). As time increases (from 0s to 180s), the temperature also increases (from 22°C to 100°C). A horizontal line would mean temperature is constant, a vertical line is impossible for this data (time and temperature are both changing), and a line rising from right to left would mean temperature decreases as time increases (which is not the case here). So the line graph should be a straight line rising from left to right as time (left - right on x - axis) and temperature (y - axis) have a positive linear relationship (we can check the differences: from 0 - 30s, $\Delta T = 35 - 22 = 13$; 30 - 60s, $\Delta T = 48 - 35 = 13$; 60 - 90s, $\Delta T = 61 - 48 = 13$; etc., so it's a linear increase).

Answer:

D) a straight line rising from left to right