D.
Blue litmus paper turns red when placed in a base.
Oxygen gas was most likely absent from Earth's primitive atmosphere. The current theory is that the Earth's early atmosphere was composed of mainly carbon dioxide and methane due to the high volcanic activity. Cyanobacteria and their use of photosynthesis was what caused earth's atmosphere to become oxygen enriched.
I hope that helps.
Answer:
15.89grams
Explanation:
The mass of a substance can be calculated from it's mole value by using the formula:
mole = mass/molar mass
According to this question, there are 0.250 moles of copper. Hence, the mass of copper can be calculated as follows:
Molar mass of Cu = 63.55g/mol
0.250 = mass/63.55
mass = 0.250 × 63.55
mass = 15.8875
Mass of Cu in 0.250mol is 15.89grams.
Answer:
C) Highly reactive
Explanation:
An atom with one or two valence electrons more than a closed shell is highly reactive, because the extra valence electrons are easily removed to form a positive ion
