Answer:
Activating a glow stick is the example of a chemical change, as snapping one will cause a chemical reaction, causing the glow. All of the other options are physical changes because nothing new is formed. Hope this helps!
Answer:
I kinda forgot but let me think
A buffer is usually composed of either:
- a weak base combined with its conjugate acid, or
- a weak acid combined with its conjugate base
Now, examining each of the choices:
1- KOH and NH3: since they are both bases, thus this mixture is not a buffer
2- HBr and NaCl: since HBr is a strong acid while NaCl is the salt of another different acid, thus this mixture is not a buffer
3- HCl and HBr: these are both considered to be strong acid, thus this mixture is not a buffer
4- HCHO2 and NaCHO2: as for HCH02, it is considered a weak base while NaCHO2 is considered its conjugate base, thus this mixture is a buffer
I believe the correct answer from the choices listed above is the first option. The element that would most likely have a positive electron affinity would be sodium, Na. Electron affinity is defined as the change in energy of a neutral atom when an electron is added to the atom.
