Question

(01.04 mc)
matt has four samples of substances:
sample a: 8 ml of hydrogen gas
sample b: 5 ml of helium gas
sample c: 5 ml of oxygen gas
sample d: 8 ml of helium gas
which of the following samples have the same density?
○ sample a and sample d
○ sample b and sample d
○ sample b and sample c
○ sample a and sample b

Explanation:

Step1: Recall density formula

Density ($
ho$) is defined as mass ($m$) divided by volume ($V$), i.e., $
ho = \frac{m}{V}$. For a given substance (at constant temperature and pressure), the density is constant because the mass - to - volume ratio is fixed. So, samples of the same substance will have the same density, regardless of the volume of the sample.

Step2: Identify substances in each sample

• Sample A: Hydrogen gas ($\ce{H_2}$)
• Sample B: Helium gas ($\ce{He}$)
• Sample C: Oxygen gas ($\ce{O_2}$)
• Sample D: Helium gas ($\ce{He}$)

Step3: Compare samples for same substance

We can see that Sample B and Sample D are both samples of helium gas. Since they are the same substance, their density (mass/volume ratio) will be the same, even though their volumes (5 mL and 8 mL) are different.

Answer:

Sample B and Sample D