a comparision of density value bx x-ray reveals that % of Al are 0.07% at 923 K and 0.009% at 757 K
To compare the density values of aluminum (Al) at different temperatures, you need to gather information about the densities of Al at those specific temperatures. The percent values you mentioned are not sufficient on their own to make a direct comparison of density.
To find the density values, you can refer to a reliable source of data, such as a materials handbook or an online database. These sources typically provide tables or graphs that show the density values of various materials, including aluminum, at different temperatures.
Once you have the density values for Al at 923 K and 757 K, you can calculate the comparison by using the following formula:
Density comparison = (Density at 923 K - Density at 757 K) / Density at 757 K * 100
For example, if the density of Al at 923 K is 2.7 g/cm³ and the density at 757 K is 2.5 g/cm³, the calculation would be:
Density comparison = (2.7 - 2.5) / 2.5 * 100 = 8%
This comparison indicates that the density of Al increases by 8% when the temperature increases from 757 K to 923 K.