Answer:
Carbon Dioxide
Explanation:
Plants inhale Carbon Dioxide and exhale Oxygen
The mantle has a mass of around
that is around 68.4% of earth's mass.
So to calculate moles we need to first find out the mass of oxygen and silicon present in mantle. It is given that oxygen is 44.8% by mass in mantle and 21.5% by mass in mantle, therefore to calculate its mass, we need to use 
Now, to calculate mass percentage of oxygen


Similarly the mass of silicon can be calculated

Now, the moles of any substance is calculated by


where, mass of oxygen in kilograms is 
So,
Similarly 

Now, to calculate mole ratio we need to divide every moles to the lowest calculated mole that is the moles of Si and round it off to the nearest whole number.





Answer:
One independent variable
Explanation:
The other variables are called controlled variables because the experiment is designed to keep them at an unchanging value, known as "controlling" a variable. A valid experiment should have only one independent variable.
Answer is B- F has a smaller radius than F− because an additional electron causes greater repulsion in F− is the correct choice and the nuclear charge the radius of the anion increases.
Explanation: I hoped that helped!