Answer:
a. Heat is often absorbed during reactions.
c. Heat is often released during chemical reactions.
Explanation:
Thermochemistry -
The study of thermochemistry involve the change in the amount of heat , during any physical or chemical process , is referred to as thermodynamics .
The focus of thermochemistry is on the changing amount of energy in the form of heat , on the system with respect to the surroundings .
The process like boiling , melting , sublimation , may require energy or releases energy , and hence are studied under thermochemistry .
Hence , from the given question ,
The correct options are - a , c.
Answer:
They went from atoms to oxygen molecule.
Explanation:
I'm not sure if this is the answer your teacher is looking for, but in simple terms you had 2 oxygen atoms. Together they make an oxygen molecule, which is the stuff we breathe.
Answer:
(3) NaNO₃
Step-by-step explanation:
Sodium nitrate has ionic bonds, because it consists of Na⁺ and NO₃⁻ ions.
However, the nitrate ions have <em>covalent bonds</em> between the O atoms and the central N atoms.
(1) and (2) are <em>wrong</em>. Both N₂O₅ and HCl consist of nonmetals, so they are <em>covalent</em> compounds.
(4) is <em>wrong</em>. NaCl has <em>only ionic bonds</em> between the Na⁺ and Cl⁻ ions