Answer: This contains magnesium, Mg2+, and hydroxide, OH–
, ions. Each magnesium ion is +2 and
each hydroxide ion is -1: two -1 ions are needed for one +2 ion, and the formula for magnesium
hydroxide is Mg(OH)2. The (OH)2 indicates there are two OH–
ions. In a formula unit of
Mg(OH)2, there are one magnesium ion and two hydroxide ions; or one magnesium, two
oxygen, and two hydrogen atoms. The subscript multiplies everything in ( )
hope that helped!!
Cathode rays are a stream of negatively charged particles or electrons in vacuum tubes. They were first seen by Johann Hittorf in 1869. They are named since they are emitted by electrode or cathode. In order to release the electrons, the electrons should first be detached from the atoms of the cathode.
Answer:
A) Ca(s) + C(s) + 3/2 O₂(g) → CaCO₃(s)
Explanation:
Standard enthalpy of formation of a chemical is defined as the change in enthalpy durin the formation of 1 mole of the substance from its constituent elements in their standard states.
The consituent elements of calcium carbonate, CaCO₃, in their standard states (States you will find this pure elements in nature), are:
Ca(s), C(s) and O₂(g)
That means, the equation that represents standard enthalpy of CaCO₃ is:
<h3>A) Ca(s) + C(s) + 3/2 O₂(g) → CaCO₃(s)</h3><h3 />
<em>Is the equation that has ΔH° = -1207kJ/mol</em>
The correct should be A. thousands of galaxies
