Answer:
The heat of reaction when hydrogen and oxygen combine to form water is :
<u>C. 571.6 kJ</u>
Explanation:
Enthalpy Change = The enthalpy change for the formation of 1 mole of the substance from their standard state is called the enthalpy of formation.
This is intensive quantity as it is fixed for 1 mole .
Intensive properties = Those properties which are independent on the amount of the substance are intensive properties.
The value of these quantities does not get halve if you divide the substance into two equal parts. example , density, refractive index.
However , the enthalpy of reaction is extensive. Because on increasing the amount the value of the enthalpy also get doubles
Hence for this reaction :

Its value is -285.8 kJ for 1 mole
And here two moles are present . so the value of molar enthalpy is:
-285.8 x 2 = -571.6 kJ
HNO3 and H2SO4 are Arrhenius acids which will increase the concentration of H+ when dissolved in water.
KOH and Ca(OH)2 are Arrhenius bases that increase the concentration of OH- when dissociated in water.
Answer:
One positive charge
Explanation:
In a neutral atom, the number of positive and negative particles are equal. This leaves the atom with a net charge of zero, 0.
When the number of protons in an atom is greater than the number of electrons, the atom becomes positively charged. When an atom loses an electron when a bond wants to form, it has a net positive charge.
The number of electrons lost or gained determines the charge.
Well theres not a question but a covalent bond is when you share electrons.