Question

read the passage and answer the next two questions. during a classroom experiment, a burning magnesium ribbon was dropped into a glass test tube filled with oxygen. a bright white flame was produced. a white powdery substance formed at the end of the reaction. which of the following statements about the element from which the ribbon was made, are true? select all that apply. it has two valence electrons it belongs to the third period it belongs to the third group it has three valence electrons

Explanation:

Step1: Identify the element

The ribbon is magnesium.

Step2: Recall magnesium's properties

Magnesium has atomic number 12. Its electron - configuration is 1s²2s²2p⁶3s².

Step3: Analyze valence electrons

From the electron - configuration, it has 2 valence electrons (3s²).

Step4: Analyze period and group

It is in the third period (because the outermost electrons are in the n = 3 shell) and in the second group (because it has 2 valence electrons).

Answer:

It has two valence electrons.
It belongs to the third period.