They are considered the basic units of matter because all mass is made of atoms.
U-238
The number besides the U means its total molar mass. The molar mass of this element is 238
Molar mass= protons + neutrons
This means that 238= 146 + protons
Do 238 - 146
Answer is 92
Answer:
carbon dioxide is a gas so it isn't collected over water.
Explanation:
it works for insoluble gases such as hydrogen,or gases that do not dissolve easily in water such as ammonia and chlorine are readily soluble in water and are not collected this way.
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Wood is a Heterogeneous Mixture.
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Answer: Option (b) is the correct answer.
Explanation:
A chemical reaction in which heat energy is absorbed by the reactant molecules is known as an endothermic reaction.
Therefore, upon completion of this reaction the container in which reaction is carried out becomes colder.
A chemical reaction in which heat energy is released by the reactant molecules is known as an exothermic reaction.
Therefore, upon completion or during this type of reaction the container in which reaction is carried out becomes hot.
Thus, we can conclude that when the test tube gets colder as the reaction takes place then it means this chemical reaction is endothermic reaction.
