<h2>
contains both covalent and ionic bonds.</h2>
Explanation:
A covalent bond is formed when an element shares its valence electron with another element. This bond is formed between two non metals.
An ionic bond is formed when an element completely transfers its valence electron to another element. The element which donates the electron is known as electropositive element or the metal and the element which accepts the electrons is known as electronegative element or non metal.
a.
contain covalent bonds as they are made up of non metals only.
b.
contain ionic bonds as they are made up of sodium metal and fluorine non metal.
c.
contain covalent bonds as they are made up of non metals only.
d.
contain ionic bonds between
and
and covalent between N and H in 
Learn more about ionic and covalent bonds
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Answer: C(s) + O2(g) --> CO2(g)12g (C) .... 50.8g (O2)................. initial amounts0g(C) .........18.8g(O2) ................. amounts when reaction completeThat means that C was the limiting reactant, and the amount of CO2 is based on the amount of carbon that burned. Covert 12 grams of carbon to moles. The moles of CO2 will be the same, since they are in a 1:1 mole ratio. Then convert the moles of CO2 to grams.12g C x (1 mol C / 12.0 g C) x (1 mol CO2 / 1 mol C) x (44.0g CO2 / 1 mol CO2) =44 g of CO2
Chemical reaction that absorbs heat from its environment
Answer: Meteorhpayne
Explanation: Correct me if im wrong :(