Question

1. choose the best answer.

which of the following is an anion?
kcl
l+
na+
cn-

1. order the atomic models with the top being the oldest model and the bottom being the latest.

Explanation:

Step1: Define anion

An anion is a negatively - charged ion.

Step2: Analyze each option

• KCl is a compound, not an ion.
• L+ and Na+ are cations (positively - charged ions).
• CN− is a negatively - charged ion, so it is an anion.

Answer:

CN−

For question 5, the common atomic models in chronological order from oldest to latest are:

• The Dalton's solid - sphere model (represented by the simple sphere).
• The Thomson's plum - pudding model (where electrons are embedded in a positive sphere like plums in a pudding).
• The Rutherford's nuclear model (with a small, dense nucleus and electrons orbiting around it).
• The Bohr's model (with electrons in fixed orbits at specific energy levels).
• The quantum mechanical model (the most modern one, describing electrons in terms of probability clouds).

Since the images seem to represent the solid - sphere and plum - pudding models, if we assume the simple sphere is the solid - sphere model and the one with embedded particles is the plum - pudding model, the order from oldest to latest would be:

1. The simple sphere (Dalton's solid - sphere model)
2. The model with embedded particles (Thomson's plum - pudding model)