19 protons and 19 electrons but neutrons are vary
Layer 2 and layer 9 are the same relative age.
Explanation:
The statement that best describes the rock layers is that Layer 2 and layer 9 are the same relative age..
The relative age is used in placing sedimentary rocks in order of their occurrence.
To do this, we apply the sedimentary laws.
The ones applicable here are:
- Principle of superposition states that in an undisturbed sequence, the oldest layer is at the base and youngest on top.
- Principle of cross cutting states that a fault and intrusion are younger than the rocks they cut through.
- Principle of fossil and fauna succession states that fossils and fauna succeed on another in a determinable form.
We see that layers 2 and 9 have the same fossil and are the same lithological units.
learn more:
Sedimentary rocks brainly.com/question/2740663
#learnwithBrainly
Answer : The correct option is, (b) 22.5 M
Explanation : Given,
Mass of calcium nitrate tetrahydrate = 266 g
Molar mass of calcium nitrate tetrahydrate = 236.15 g/mole
Volume of solution = 
Molarity : It is defined as the moles of solute present in one liter of solution.
Formula used :

Now put all the given values in this formula, we get:

As calcium nitrate tetrahydrate dissociate to give 1 mole of calcium ion, 2 moles of nitrate ion and 4 moles of water.
The concentration of nitrate ion = 
Thus, the concentration of nitrate ion is, 22.5 M
When magnesium is burned, it reacts with oxygen in air not with the fire. The fire is the energy needed for the reaction to happen. Magnesium reacts with oxygen forming magnesium oxide. The light emitted from the reaction is because the reaction produced a lot of heat.
The correct answer is carbon dioxide and water vapor
These negative gasses get modified and then remain in the atmosphere without the possibility of leaving, which is why the greenhouse effect occurs.