Question

1. the following graph shows how the concentration (amount per unit volume) changes with time. what information can be obtained from the data? concentration of a reactant as a function of time 0.20 0.15 concentration (mol/liter) 0.10 0.05 0.00 0 100 200 300 400 500 600 time (seconds) a. the amount of reactant does not change with time. b. the amount of reactant first decreases and then stays constant. c. the amount of product is decreasing. d. at 300 seconds, the concentration of the reactant is at maximum. 24. apply pressure gas gas as the pressure of a gas increase at constant temperature, the volume of the gas decreases. if you a diver and you wanted to take on oxygen tank with you, what would you do? a. increase the temperature of oxygen in the tank, so that the cold oxygen doesnt damage the lungs b. decrease the pressure of oxygen in the tank, so the tank doesnt explode. c. increase the temperature of the oxygen and decrease the pressure, so the volume stays the same. d. pressurize the oxygen, so more of it can fit in a tank of a manageable size. ****************************** page 6 of 6 name roll number subject kbtc university batch general educational development test(ged) final exam kbtc time allowed – 1 hour & 30 minutes 60 marks physical science and earth and space science- 60 marks 1 in which order are the objects listed formed during the life cycle of a star? 3 marks a. protostar > red giant > supernova > stable star

Explanation:

Question 23

Step1: Analyze Option A

The graph shows concentration (reactant) changes over time. The line is not flat initially, so reactant amount changes. Eliminate A.

Step2: Analyze Option B

From time 0 to ~300 seconds, the concentration (reactant) decreases (line goes down). After ~300 seconds, it's flat (constant). So reactant first decreases, then constant. This matches.

Step3: Analyze Option C

The graph is about reactant concentration, not product. We can't conclude product is decreasing. Eliminate C.

Step4: Analyze Option D

At 0 seconds, concentration is ~0.15, at 300 seconds it's ~0.05. So 300s is not maximum. Eliminate D.

The principle is: at constant temperature, pressure and volume of gas are inversely related (more pressure → less volume, and vice versa). A diver needs to carry oxygen in a manageable tank.

• Option A: Temperature increase isn't about fitting more oxygen, and cold oxygen damaging lungs is not relevant to the gas law here. Eliminate.
• Option B: Decreasing pressure would increase volume, so less oxygen fits. Not helpful for a manageable tank. Eliminate.
• Option C: The problem is about fitting more oxygen in a tank, not keeping volume same. The reasoning here is off. Eliminate.
• Option D: Pressurizing oxygen (increasing pressure) decreases its volume, so more oxygen can fit in a small (manageable) tank. This matches the gas law.

The correct star life cycle order (simplified) is: Protostar forms first, then (for a medium - mass star like Sun) it becomes a main - sequence star, then red giant, then (if massive enough) supernova, but the option given has "protostar > red giant > supernova > stable star" which has an error (stable star should be main - sequence star first, and the end for medium mass is white dwarf, not supernova). But assuming the intended correct order among the options, the first stage is protostar. So the correct option starts with protostar.

Answer:

B. The amount of reactant first decreases and then stays constant.

Question 24