Answer:sodium
Explanation: because its not hard to look on the PERIODIC TABLE
Plants do not need Oxygen because they take in <span>Carbon Dioxide and make
</span><span>Oxygen they don't need </span> <span>Oxygen</span>
Combustion can be defined as the reaction of a compound with oxygen. The enthalpy of combustion of octane is
for
.
<h3>What is the enthalpy of reaction?</h3>
The enthalpy of reaction is the amount of heat energy absorbed or lost by the molecules in the chemical reaction.
The enthalpy of combustion is the amount of heat energy released by the compound in the reaction with oxygen.
The reaction in which heat is liberated with the reaction of a compound with oxygen has an enthalpy of combustion, equivalent to the enthalpy of reaction.
The combustion of octane can be given as:

Thus, the reaction has combustion energy equivalent to the enthalpy of the reaction is
. Thus, option B is correct.
Learn more about enthalpy of reaction, here:
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Answer:
5 ppb of Cd
Explanation:
Given , Concentration = 0.0050 mg/L
To find this concentration in parts per billion
As,
1 mg per liter = 1 ppm
Parts per billion is defined as the number of the units of the mass of contaminant per thousand million units of the total mass. The relation between ppm and ppb is shown below as:
1 ppm = 1000 ppb
Concluding as:
1 mg per liter = 1000 ppb
So,
0.0050 mg/L = 1000 × 0.0050 ppb = 5 ppb of Cd