Question

18 elección múltiple 1 punto which of these is a homogeneous mixture? copper sand and water sio₂ tea 19 numérico 1 punto an atom has 10 protons, 10 neutrons, and 10 electrons. what is the mass number? respuesta 20 elección múltiple 1 punto what happens to particles in matter when thermal energy is absorbed? the particles move closer together. strong attractions are formed between particles. the particles get larger. the average speed of the particles increases.

Explanation:

Question 18

• Copper is an element (pure substance), not a mixture.
• Sand and water is a heterogeneous mixture (components are not uniformly distributed).
• \(SiO_{2}\) (silicon dioxide) is a compound (pure substance), not a mixture.
• Tea is a homogeneous mixture (components like water, dissolved tea compounds are uniformly distributed).

Step1: Recall the formula for mass number

The mass number (\(A\)) of an atom is given by the sum of the number of protons (\(p\)) and neutrons (\(n\)) in the atom. The formula is \(A=p + n\).

Step2: Substitute the given values

Given \(p = 10\) and \(n=10\). Substitute into the formula: \(A=10 + 10\).

• When thermal energy is absorbed:
• Particles do not move closer together (that would be when thermal energy is released in some phase - change cases like gas to liquid).
• Stronger attractions are not formed (attractions are related to intermolecular forces, and adding thermal energy usually weakens them in the sense of allowing more movement).
• Particles do not get larger (size of particles is a property of the substance at the particulate level and not changed by thermal energy absorption in this context).
• The average speed of the particles increases. Thermal energy is related to the kinetic energy of particles (\(KE=\frac{1}{2}mv^{2}\)), and as thermal energy (a form of kinetic energy at the particulate level) is absorbed, the average speed (\(v\)) of the particles increases.

Answer:

tea

Question 19