<span>Endothermic reactions take in heat from the environment in order to react while exothermic reactions release heat during the reaction. For this, D must be true as the products have less energy because they have released heat during the reaction. A and C are incorrect because they products and reactants are equal and B is wrong because the energy of the products would be more as the reaction took in heat.</span>
An hour is 60 minutes. So you multiple the hot by 60. You get 180 minutes plus the 75 remaining minutes. The answer is 255
The quantity pH stands for the negative logarithm of the H⁺ ions concentration in a solution. In equation form, pH = -log[H⁺], where [H⁺] is the concentration of hydrogen ion in molarity or moles/liter. Using this definition, the pH of the following substances are:
Oven Cleaner: pH =-log(10⁻¹³ M) = 13
Water: pH = -log(<span>0.0000007 M) = 6.15
Blood: pH = -log(</span><span>0.00000004 M) = 7.40
Vinegar: pH = -log(</span><span> 0.0063 M) = 2.2
The measure of the pH is important when it comes to reactions because pH is a strong factor. The net charge of a substance is a result of its pH. This charge is the basis of the degree of intermolecular forces like electrostatic attraction due to difference of charges by the substance and its substrate.</span>
Calcium is a chemical element that has an atomic number of 20. The atomic number of element just means how many protons are in the core of the particular element.
A picture of the element of calcium is attached with its atomic number.
