Answer:
Photosynthesis is the transformation of radiant energy to chemical energy. Plants take in water, carbon dioxide, and sunlight and turn them into glucose and oxygen. Called photosynthesis, one of the results of this process is that carbon dioxide is removed from the air.
Explanation:
Half-life is the time taken for the concentration of the substance to reduce by 50%. The original sample of strontium had a mass of 1.6 gms. Thus, option d is correct.
<h3>What is half-life?</h3>
The half-life of any radioactive substance is the time period at which the concentration will get reduced to half the initial amount. The initial mass of Sr-90 is calculated as,

Given,
Quantity of the remaining substance N (t) = 0.40 gm
Initial radioactive substance quantity
=?
Time duration (t) = 56 years
Half-life = 28 years
Substituting values above:

= 1.6 gm
Therefore, option d. the initial mass of Sr is 1.6 gm.
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12 moles of oxygen gas are needed to react with 24 moles of carbon monoxide.
<u>Explanation:</u>
The molar ratio of carbon monoxide to oxygen 2:1
Which means 2 moles of carbon monoxide is reacting with 1 mole of oxygen.
to produce 2 moles of carbon dioxide.
Therefore, from the molar ratio, we get that 12 moles of oxygen are required to react with 24 moles 0f carbon monoxide.
Molar ratio:
The molar ratio gives the moles of product that are formed from a certain amount of reactant, and also the number of moles of a reactant needed to react with another reactant.
Water vapor
Its still water(H2O)
Just in the gas form