Answer: Option (A) is the correct answer.
Explanation:
An element is defined as a substance that contains atoms of same type.
As copper wire is a substance that is made up of only atoms of copper. And, all these atoms of copper will be the same. Hence, it is an element.
This means that all the atoms of copper will have same number of protons, neutrons and electrons.
Thus, we can conclude that the statement they are all exactly the same best describes the copper atoms.
<u>Answer:</u> The freezing point of solution is 2.6°C
<u>Explanation:</u>
To calculate the depression in freezing point, we use the equation:

Or,

where,
= 
Freezing point of pure solution = 5.5°C
i = Vant hoff factor = 1 (For non-electrolytes)
= molal freezing point depression constant = 5.12 K/m = 5.12 °C/m
= Given mass of solute (anthracene) = 7.99 g
= Molar mass of solute (anthracene) = 178.23 g/mol
= Mass of solvent (benzene) = 79 g
Putting values in above equation, we get:

Hence, the freezing point of solution is 2.6°C
Answer:
2.8g/cm³
Explanation:
Given parameters:
Mass of cube = 42g
Volume of cube = 15cm³
Unknown:
Density of the cube = ?
Solution:
Density is defined as the mass per unit volume of a substance. It is mathematically expressed as:
Density =
So;
Density =
= 2.8g/cm³